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+The Project Gutenberg EBook of Are the Effects of Use and Disuse Inherited?, by 
+William Platt Ball
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Are the Effects of Use and Disuse Inherited?
+       An Examination of the View Held by Spencer and Darwin
+
+Author: William Platt Ball
+
+Release Date: August 26, 2008 [EBook #26438]
+
+Language: English
+
+Character set encoding: ISO-8859-1
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+*** START OF THIS PROJECT GUTENBERG EBOOK THE EFFECTS OF USE AND DISUSE ***
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+
+ _NATURE SERIES_
+
+
+               ARE THE EFFECTS OF USE AND
+                    DISUSE INHERITED?
+
+           _AN EXAMINATION OF THE VIEW HELD BY
+                   SPENCER AND DARWIN_
+
+
+                           BY
+                   WILLIAM PLATT BALL
+
+
+                         LONDON
+                    MACMILLAN AND CO.
+                      AND NEW YORK
+                          1890
+
+ _The Right of Translation and Reproduction is Reserved_
+
+
+
+
+ RICHARD CLAY AND SONS, LIMITED,
+       LONDON AND BUNGAY.
+
+
+
+
+PREFACE.
+
+
+My warmest thanks are due to Mr. Francis Darwin, to Mr. E. B. Poulton
+(whose interest in the subject here discussed is shown by his share in
+the translation of Weismann's _Essays on Heredity_), and to Professor
+Romanes, for the help afforded by their kindly suggestions and
+criticisms, and for the advice and recommendation under which this essay
+is now published. Encouragement from Mr. Francis Darwin is to me the
+more precious, and the more worthy of grateful recognition, from the
+fact that my general conclusion that acquired characters are _not_
+inherited is at variance with the opinion of his revered father, who
+aided his great theory by the retention of some remains of Lamarck's
+doctrine of the inherited effect of habit. I feel as if the son, as
+representative of his great progenitor, were carrying out the idea of an
+appreciative editor who writes to me: "We must say that if Darwin were
+still alive, he would find your arguments of great weight, and
+undoubtedly would give to them the serious consideration which they
+deserve." I hope, then, that I may be acquitted of undue presumption in
+opposing a view sanctioned by the author of the _Origin of Species_, but
+already stoutly questioned and firmly rejected by such followers of his
+as Weismann, Wallace, Poulton, Ray Lankester, and others, to say nothing
+of its practical rejection by so great an authority on heredity as
+Francis Galton.
+
+The sociological importance of the subject has already been insisted on
+in emphatic terms by Mr. Herbert Spencer, and this importance may be
+even greater than he imagined.
+
+Civilization largely sets aside the harsh but ultimately salutary action
+of the great law of Natural Selection without providing an efficient
+substitute for preventing degeneracy. The substitute on which moralists
+and legislators rely--if they think on the matter at all--is the
+cumulative inheritance of the beneficial effects of education, training,
+habits, institutions, and so forth--the inheritance, in short, of
+acquired characters, or of the effects of use and disuse. If this
+substitute is but a broken reed, then the deeper thinkers who gradually
+teach the teachers of the people, and ultimately even influence the
+legislators and moralists, must found their systems of morality and
+their criticisms of social and political laws and institutions and
+customs and ideas on the basis of the Darwinian law rather than on that
+of Lamarck.
+
+Looking forward to the hope that the human race may become consciously
+and increasingly master of itself and of its destiny, and recognizing
+the Darwinian principle of the selection of the fittest as the _only_
+means of preventing the moral and physical degeneracy which, like an
+internal dry rot, has hitherto been the besetting danger of all
+civilizations, I desire that the thinkers who mould the opinions of
+mankind shall not be led astray from the true path of enduring progress
+and happiness by reliance on fallacious beliefs which will not bear
+examination. Such, at least, is the feeling or motive which has prompted
+me to devote much time and thought to a difficult but important inquiry
+in a debatable region of inference and conjecture, where (I am afraid)
+evidence on either side can never be absolutely conclusive, and where,
+especially, the absolute demonstration of a universal negative cannot
+reasonably be expected.
+
+
+
+
+CONTENTS.
+
+
+                                                                PAGE
+ PREFACE                                                           v
+
+ IMPORTANCE AND BEARING OF THE INQUIRY                             1
+
+ SPENCER'S EXAMPLES AND ARGUMENTS                               6-44
+   DIMINUTION OF THE JAWS                                          6
+   DIMINISHED BITING MUSCLES OF LAP-DOGS                          12
+   CROWDED TEETH                                                  14
+   BLIND CAVE-CRABS                                               17
+   NO CONCOMITANT VARIATION FROM CONCOMITANT DISUSE               17
+   THE GIRAFFE, AND NECESSITY FOR CONCOMITANT VARIATION           18
+   ALLEGED RUINOUS EFFECTS OF NATURAL SELECTION                   23
+   ADVERSE CASE OF NEUTER INSECTS                                 24
+   ĘSTHETIC FACULTIES                                             29
+   LACK OF EVIDENCE                                               34
+   INHERITED EPILEPSY IN GUINEA-PIGS                              35
+   INHERITED INSANITY AND NERVOUS DISORDERS                       36
+   INDIVIDUAL AND TRANSMISSIBLE TYPE NOT MODIFIED ALIKE           40
+
+ DARWIN'S EXAMPLES                                            45-100
+   REDUCED WINGS OF BIRDS OF OCEANIC ISLANDS                      49
+   DROOPING EARS AND DETERIORATED INSTINCTS                       53
+   WINGS AND LEGS OF DUCKS AND FOWLS                              55
+   PIGEONS' WINGS                                                 62
+   SHORTENED BREAST-BONE IN PIGEONS                               64
+   SHORTENED FEET IN PIGEONS                                      70
+   SHORTENED LEGS OF RABBITS                                      70
+   BLIND CAVE-ANIMALS                                             72
+   INHERITED HABITS                                               73
+   TAMENESS OF RABBITS                                            76
+   MODIFICATIONS OBVIOUSLY ATTRIBUTABLE TO SELECTION              82
+   SIMILAR EFFECTS OF NATURAL SELECTION AND USE-INHERITANCE       83
+   INFERIORITY OF SENSES IN EUROPEANS                             85
+   SHORT-SIGHT IN WATCHMAKERS AND ENGRAVERS                       85
+   LARGER HANDS OF LABOURERS' INFANTS                             87
+   THICKENED SOLE IN INFANTS                                      88
+   A SOURCE OF MENTAL CONFUSION                                   91
+   WEAKNESS OF USE-INHERITANCE                                    94
+
+ INHERITED INJURIES                                          101-118
+   INHERITED MUTILATIONS                                         101
+   THE MOTMOT'S TAIL                                             110
+   OTHER INHERITED INJURIES MENTIONED BY DARWIN                  111
+   QUASI-INHERITANCE                                             116
+
+ MISCELLANEOUS CONSIDERATIONS                                119-143
+   TRUE RELATION OF PARENTS AND OFFSPRING                        119
+   INVERSE INHERITANCE                                           123
+   EARLY ORIGIN OF THE OVA                                       124
+   MARKED EFFECTS OF USE AND DISUSE ON THE INDIVIDUAL            126
+   WOULD NATURAL SELECTION FAVOUR USE-INHERITANCE?               127
+   USE-INHERITANCE AN EVIL                                       128
+   VARIED EFFECTS OF USE AND DISUSE                              134
+   USE-INHERITANCE IMPLIES PANGENESIS                            137
+   PANGENESIS IMPROBABLE                                         138
+   SPENCER'S EXPLANATION OF USE-INHERITANCE                      141
+
+ CONCLUSIONS                                                 144-156
+   USE-INHERITANCE DISCREDITED AS UNNECESSARY, UNPROVEN,
+       AND IMPROBABLE                                            144
+   MODERN RELIANCE ON USE-INHERITANCE MISPLACED                  145
+
+
+
+
+ARE THE EFFECTS OF USE AND DISUSE INHERITED?
+
+
+
+
+IMPORTANCE AND BEARING OF THE INQUIRY.
+
+
+The question whether the effects of use and disuse are inherited, or, in
+other words, whether acquired characters are hereditary, is of
+considerable interest to the general student of evolution; but it is, or
+should be, a matter of far deeper interest to the thoughtful
+philanthropist who desires to ensure the permanent welfare and happiness
+of the human race. So profoundly important, in fact, are the moral,
+social, and political conclusions that depend on the answer to this
+inquiry, that, as Mr. Herbert Spencer rightly says, it "demands, beyond
+all other questions whatsoever, the attention of scientific men."
+
+It is obvious that we can produce important changes in the individual.
+We can, for example, improve his muscles by athletics, and his brain by
+education. The use of organs enlarges and strengthens them; the disuse
+of parts or faculties weakens them. And so great is the power of habit
+that it is proverbially spoken of as "second nature." It is thus certain
+that we can modify the individual. We can strengthen (or weaken) his
+body; we can improve (or deteriorate) his intellect, his habits, his
+morals. But there remains the still more important question which we are
+about to consider. Will such modifications be inherited by the offspring
+of the modified individual? Does individual improvement transmit itself
+to descendants independently of personal teaching and example? Have
+artificially produced changes of structure or habit any inherent
+tendency to become congenitally transmissible and to be converted in
+time into fixed traits of constitution or character? Can the
+philanthropist rely on such a tendency as a hopeful factor in the
+evolution of mankind?--the only sound and stable basis of a higher and
+happier state of things being, as he knows or ought to know, the innate
+and constitutionally-fixed improvement of the race as a whole. If
+acquired modifications are impressed on the offspring and on the race,
+the systematic moral training of individuals will in time produce a
+constitutionally moral race, and we may hope to improve mankind even in
+defiance of the unnatural selection by which a spurious but highly
+popular philanthropy would systematically favour the survival of the
+unfittest and the rapid multiplication of the worst. But if acquired
+modifications do not tend to be transmitted, if the use or disuse of
+organs or faculties does not similarly affect posterity by inheritance,
+then it is evident that no innate improvement in the race can take place
+without the aid of natural or artificial selection.
+
+Herbert Spencer maintains that the effects of use and disuse _are_
+inherited in kind, and in his _Factors of Organic Evolution_[1] he has
+supported his contention with a selection of facts and reasonings which
+I shall have the temerity to examine and criticize. Darwin also held the
+same view, though not so strongly. And here, to prevent
+misunderstanding, I may say that the admiration and reverence and
+gratitude due to Darwin ought not to be allowed to interfere in the
+slightest degree with the freest criticism of his conclusions. To
+perfect his work by the correction of really extraneous errors is as
+much a sacred duty as to study and apply the great truths he has taught.
+
+
+FOOTNOTES:
+
+[1] Which originally appeared in the _Nineteenth Century_ for April and
+May, 1886.
+
+
+
+
+SPENCER'S EXAMPLES AND ARGUMENTS.
+
+
+DIMINUTION OF THE JAWS IN CIVILIZED RACES.
+
+Mr. Spencer verified this by comparing English jaws with Australian and
+Negro jaws at the College of Surgeons.[2] He maintains that the
+diminution of the jaw in civilized races can _only_ have been brought
+about by inheritance of the effects of lessened use. But if English jaws
+are lighter and thinner than those of Australians and Negroes, so too is
+the rest of the skull. As the diminution in the weight and thickness of
+the walls of the cranium cannot well be ascribed to disuse, it must be
+attributed to some other cause; and this cause may have affected the jaw
+also. Cessation of the process by which natural selection[3] favoured
+strong thick bones during ages of brutal violence might bring about a
+change in this direction. Lightness of structure, facilitating agility
+and being economical of material, would also be favoured by natural
+selection so far as strength was not too seriously diminished.
+
+Sexual selection powerfully affects the human face, and so must affect
+the jaws--as is shown by the differences between male and female jaws,
+and by the relative lightness and smallness of the latter, especially in
+the higher races. Human preference, both sexual and social, would tend
+to eliminate huge jaws and ferocious teeth when these were no longer
+needed as weapons of war or organs of prehension, &c. We can hardly
+assume that the lower half of the face is specially exempt from the
+influence of natural and sexual selection; and the effects of these
+undoubted factors of evolution must be fully considered before we are
+entitled to call in the aid of a factor whose existence is questioned.
+
+After allowing for lost teeth and the consequent alveolar absorption,
+and for a reduction proportional to that shown in the rest of the skull,
+the difference in average weight in fifty European and fourteen
+Australian male jaws at the College of Surgeons turned out to be less
+than a fifth of an ounce, or about 5 per cent. This slight reduction may
+be much more than accounted for by such causes as disuse in the
+individual, human preference setting back the teeth, and partial
+transference of the much more marked diminution seen in female jaws.
+There is apparently no room for accumulated _inherited_ effects of
+ancestral disuse. The number of jaws is small, indeed; but weighing them
+is at least more decisive than Mr. Spencer's mere inspection.
+
+The differences between Anglo-Saxon male jaws and Australian and
+Tasmanian jaws are most easily explained as effects of human preference
+and natural selection. We can hardly suppose that disuse would maintain
+or develop the projecting chin, increase its perpendicular height till
+the jaw is deepest and strongest at its extremity, evolve a side flange,
+and enlarge the upper jaw-bone to form part of a more prominent nose,
+while drawing back the savagely obtrusive teeth and lips to a more
+pleasing and subdued position of retirement and of humanized beauty. If
+human preference and natural selection caused some of these differences,
+why are they incompetent to effect changes in the direction of a
+diminution of the jaw or teeth? And if use and disuse are the sole
+modifying agents in the case of the human jaw, why should men have any
+more chin than a gorilla or a dog?
+
+The excessive weight of the West African jaws at the College of Surgeons
+is partly _against_ Mr. Spencer's contention, unless he assumes that
+Guinea Negroes use their jaws far more than the Australians, a
+supposition which seems extremely improbable. The heavier skull and
+narrower molar teeth point however to other factors than increased use.
+
+The striking variability of the human jaw is strongly opposed to the
+idea of its being under the direct and dominant control of so uniform a
+cause as ancestral use and disuse. Mr. Spencer regards a variation of 1
+oz. as a large one, but I found that the English jaws in the College of
+Surgeons varied from 1·9 oz. to 4·3 oz. (or 5 oz. if lost teeth were
+allowed for); Australian jaws varied from 2 oz. to 4·5 oz. (with _no_
+lost teeth to allow for); while in Negro jaws the maximum rose to over
+5-1/2 oz.[4] In spite of disuse some European jaws were twice as heavy
+as the lightest Australian jaw, either absolutely or (in some cases)
+relatively to the cranium. The uniformity of change relied upon by Mr.
+Spencer is scarcely borne out by the facts so far as male jaws are
+concerned. The great reduction in the weight of _female_ jaws _and
+skulls_ evidently points to sexual selection and to panmixia under male
+protection.
+
+I think, on the whole, we must conclude that the human jaws do not
+afford satisfactory proof of the inheritance of the effects of use and
+disuse, inasmuch as the differences in their weight and shape and size
+can be more reasonably and consistently accounted for as the result of
+less disputable causes.
+
+
+DIMINISHED BITING MUSCLES OF LAP-DOGS.
+
+The next example, the reduced biting muscles, &c., of lap-dogs is also
+unsatisfactory as a proof of the inheritance of the effects of disuse;
+for the change can readily be accounted for without the introduction of
+such a factor. The previous natural selection of strong jaws and teeth
+and muscles is reversed. The conscious or unconscious selection of
+lap-dogs with the least tendency to bite would easily bring about a
+general enfeeblement of the whole biting apparatus--weakness of the
+parts concerned favouring harmlessness. Mr. Spencer maintains that the
+dwindling of the parts concerned in clenching the jaw is certainly not
+due to artificial selection because the modifications offer no
+appreciable external signs. Surely hard biting is sufficiently
+appreciable by the person bitten without any visual admeasurement of the
+masseter muscles or the zygomatic arches. Disuse during lifetime would
+also cause some amount of degeneracy; and I am not sure that Mr. Spencer
+is right in _entirely_ excluding economy of nutrition from the problem.
+Breeders would not over-feed these dogs; and the puppies that grew most
+rapidly would usually be favoured.
+
+
+CROWDED TEETH.
+
+The too closely-packed teeth in the "decreasing" jaws of modern men (p.
+13)[5] are also suggestive of other causes than use and disuse. Why is
+there not simultaneous variation in teeth and jaws, if disuse is the
+governing factor? Are we to suppose that the size of the human teeth is
+maintained by use at the same time that the jaws are being diminished by
+disuse? Mr. Spencer acknowledges that the crowding of bull-dogs' and
+lap-dogs' teeth is caused by the artificial selection of shortened jaws.
+If a similar change is really occurring in man, could it not be
+similarly explained by some factor, such as sexual selection, which
+might affect the outward appearance at the cost of less obvious defects
+or inconveniences?
+
+Mr. Spencer points to the decay of modern teeth as a sign or result of
+their being overcrowded through the diminution of the jaw by disuse.[6]
+But the teeth which are the most frequently overcrowded are the lower
+incisors. The upper incisors are less overcrowded, being commonly
+pressed outwards by the lower arc of teeth fitting inside them in
+biting. The lower incisors are correspondingly pressed inwards and
+closer together. Yet the upper incisors decay--or at least are
+extracted--about twenty times as frequently as the closely packed lower
+incisors.[7] Surely this must indicate that the cause of decay is not
+overcrowding.
+
+The lateness and irregularity of the wisdom teeth are sometimes
+supposed to indicate their gradual disappearance through want of room in
+a diminishing jaw. But a note on Tasmanian skulls in the _Catalogue of
+the College of Surgeons_ (p. 199) shows that this lateness and
+irregularity have been common among Tasmanians as well as among
+civilized races, so that the change can hardly be attributed to the
+effects of disuse under civilization.
+
+
+BLIND CAVE-CRABS.
+
+The cave-crabs which have lost their disused eyes but _not the disused
+eye-stalks_ appear to illustrate the effects of natural selection rather
+than of disuse. The loss of the exposed, sensitive, and
+worse-than-useless eye, would be a decided gain, while the disused
+eye-stalk, being no particular detriment to the crab, would be but
+slightly affected by natural selection, though open to the cumulative
+effects of disuse. The disused but better protected eyes of the blind
+cave-rat are still "of large size" (_Origin of Species_, p. 110).
+
+
+NO CONCOMITANT VARIATION FROM CONCOMITANT DISUSE.
+
+It is but fair to add that these instances of the cave-crab's eye-stalk
+and the closely-packed teeth are put forward by Mr. Spencer with the
+more immediate object of proving that there is "no concomitant
+variation in co-operative parts," even when "formed out of the same
+tissue, like the crab's eye and its peduncle" (pp. 12-14, 23, 33). It
+escapes his notice, however, that in two out of his three cases it is
+_disuse_, or _diminished use_, which fails to cause concomitant
+variation or proportionate variation.
+
+
+THE GIRAFFE, AND NECESSITY FOR CONCOMITANT VARIATION.
+
+Having unwittingly shown that lessened use of closely-connected and
+co-operative parts does not cause concomitant variation in these parts,
+Mr. Spencer concludes that the concomitant variation requisite for
+evolution can only be caused by altered degrees of use or disuse. He
+elaborately argues that the many co-ordinated modifications of parts
+necessitated by each important alteration in an animal are so complex
+that they cannot possibly be brought about except by the inherited
+effect of the use and disuse of the various parts concerned. He holds,
+for instance, that natural selection is inadequate to effect the
+numerous concomitant changes necessitated by such developments as that
+of the long neck of the giraffe. Darwin, however, on the contrary, holds
+that natural selection alone "would have sufficed for the production of
+this remarkable quadruped."[8] He is surprised at Mr. Spencer's view
+that natural selection can do so little in modifying the higher animals.
+Thus one of the chief arguments with which Mr. Spencer supports his
+theory is so poorly founded as to be rejected by a far greater authority
+on such subjects. All that is needed is that natural selection should
+preserve the tallest giraffes through times of famine by their being
+able to reach otherwise inaccessible stores of foliage. The continual
+variability of all parts of the higher animals gives scope for
+innumerable changes, and Nature is not in a hurry. Mr. Spencer, however,
+says that "the chances against any adequate readjustments fortuitously
+arising must be infinity to one." But he has also shown that altered
+degree of use does not cause the needed concomitant variation of
+co-operative parts. So the chances against a beneficial change in an
+animal must be, at a liberal estimate, infinity to two. Mr. Spencer, if
+he has proved anything, has proved that it is practically impossible
+that the giraffe can have acquired a long neck, or the elk its huge
+horns, or that any species has ever acquired any important modification.
+
+Mr. Wallace, in his _Darwinism_, answers Mr. Spencer by a collection of
+facts showing that "variation is the rule," that the range of variation
+in wild animals and plants is much greater than was supposed, and that
+"each part varies to a considerable extent independently" of other
+parts, so that "the materials constantly ready for natural selection to
+act upon are abundant in quantity and very varied in kind." While
+co-operative parts would often be more or less correlated, so that they
+would tend to vary together, coincident variation is not necessary. The
+lengthened wing might be gained in one generation, and the strengthened
+muscle at a subsequent period; the bird in the meanwhile drawing upon
+its surplus energy, aided (as I would suggest) by the strengthening
+effect of increased use in the individual. Seeing that artificial
+selection of complicated variations has modified animals in many points
+either simultaneously or by slow steps, as with otter-sheep, fancy
+pigeons, &c. (many of the characters thus obtained being clearly
+independent of use and disuse), natural selection must be credited with
+similar powers, and Mr. Wallace concludes that Mr. Spencer's
+insuperable difficulty is "wholly imaginary."
+
+The extract concerning a somewhat similar "class of difficulties," which
+Mr. Spencer quotes from his _Principles of Biology_, is faulty in its
+reasoning,[9] though legitimate in its conclusion concerning the
+increasing difficulty of evolution in proportion with the increasing
+number and complexity of faculties to be evolved. But this increasing
+difficulty of complex evolution is only overcome by _some_
+favourably-varying individuals and species--not by all. And as the
+difficulty increases we find neglect and decay of the less-needed
+faculties--as with domesticated animals and civilized men, who lose in
+one direction while they gain in another. The increasing difficulty of
+complex evolution by natural selection is no proof whatever of
+use-inheritance[10] except to those who confound difficulty with
+impossibility.
+
+
+ALLEGED RUINOUS EFFECTS OF NATURAL SELECTION.
+
+Mr. Spencer further contends that natural selection, by unduly
+developing specially advantageous modifications without the necessary
+but complex secondary modifications, would render the constitution of a
+variety "unworkable" (p. 23). But this seems hardly feasible, seeing
+that natural selection must continually favour the most workable
+constitutions, and will only preserve organisms in proportion as they
+combine general workableness with the special modification. On the other
+hand, according to Mr. Spencer himself, use-inheritance must often
+disturb the balance of the constitution. Thus it tends to make the jaws
+and teeth unworkable through the overcrowding and decay of the
+teeth--there being, as his illustrations show, no simultaneous or
+concomitant or proportional variation in relation to altered degree of
+use or disuse.
+
+
+ADVERSE CASE OF NEUTER INSECTS.
+
+Mr. Spencer also holds that most mental phenomena, especially where
+complex or social or moral, can only be explained as arising from
+use-inheritance, which becomes more and more important as a factor of
+evolution as we advance from the vegetable world and the lower grades of
+animal life to the more complex activities, tastes, and habits of the
+higher organizations (preface, and p. 74). But there happens to be a
+tolerably clear proof that such changes as the evolution of complicated
+structures and habits and social instincts _can_ take place
+independently of use-inheritance. The wonderful instincts of the working
+bees have apparently been evolved (at least in all their later social
+complications and developments) without the aid of use-inheritance--nay,
+in spite of its utmost opposition. Working bees, being infertile
+"neuters," cannot as a rule transmit their own modifications and habits.
+They are descended from countless generations of queen bees and drones,
+whose habits have been widely different from those of the workers, and
+whose structures are dissimilar in various respects. In many species of
+ants there are two, and in the leaf-cutting ants of Brazil there are
+_three_, kinds of neuters which differ from each other and from their
+male and female ancestors "to an almost incredible degree."[11] The
+soldier caste is distinguished from the workers by enormously large
+heads, very powerful mandibles, and "extraordinarily different"
+instincts. In the driver ant of West Africa one kind of neuter is three
+times the size of the other, and has jaws nearly five times as long. In
+another case "the workers of one caste alone carry a wonderful sort of
+shield on their heads." One of the three neuter classes in the
+leaf-cutting ants has a single eye in the midst of its forehead. In
+certain Mexican and Australian ants some of the neuters have huge
+spherical abdomens, which serve as living reservoirs of honey for the
+use of the community. In the equally wonderful case of the termites, or
+so-called "white ants" (which belong, however, to an entirely different
+order of insect from the ants and bees) the neuters are blind and
+wingless, and are divided into soldiers and workers, each class
+possessing the requisite instincts and structures adapting it for its
+tasks. Seeing that natural selection can form and maintain the various
+structures and the exceedingly complicated instincts of ants and bees
+and wasps and termites in direct defiance of the alleged tendency to
+use-inheritance, surely we may believe that natural selection,
+unopposed by use-inheritance, is equally competent for the work of
+complex or social or mental evolution in the many cases where the strong
+presumptive evidence cannot be rendered almost indisputable by the
+exceptional exclusion of the modified animal from the work of
+reproduction.
+
+Ants and bees seem to be capable of altering their habits and methods of
+action much as men do. Bees taken to Australia cease to store honey
+after a few years' experience of the mild winters. Whole communities of
+bees sometimes take to theft, and live by plundering hives, first
+killing the queen to create dismay among the workers. Slave ants attend
+devotedly to their captors, and fight against their own species. Forel
+reared an artificial ant-colony made up of five different and more or
+less hostile species. Why cannot a much more intelligent animal modify
+his habits far more rapidly and comprehensively without the aid of a
+factor which is clearly unnecessary in the case of the more intelligent
+of the social insects?
+
+
+ĘSTHETIC FACULTIES.
+
+The modern development of music and harmony (p. 19) is undeniable, but
+why could it only have been brought about by the help of the inheritance
+of the effects of use? Why are we to suppose that "minor traits" such as
+the "ęsthetic perceptions" cannot have been evolved by natural selection
+(p. 20) or by sexual selection? Darwin holds that our musical faculties
+were developed by sexual preference long before the acquisition of
+speech. He believes that the "rhythms and cadences of oratory are
+derived from previously developed musical powers"--a conclusion "exactly
+opposite" to that arrived at by Mr. Spencer.[12] The emotional
+susceptibility to music, and the delicate perceptions needed for the
+higher branches of art, were apparently the work of natural and sexual
+selection in the long past. Civilization, with its leisure and wealth
+and accumulated knowledge, perfects human faculties by artificial
+cultivation, develops and combines means of enjoyment, and discovers
+unsuspected sources of interest and pleasure. The sense of harmony,
+modern as it seems to be, must have been a latent and indirect
+consequence of the development of the sense of hearing and of melody.
+Use, at least, could never have called it into existence. Nature favours
+and develops enjoyments to a certain extent, for they subserve
+self-preservation and sexual and social preference in innumerable ways.
+But modern ęsthetic advance seems to be almost entirely due to the
+culture of latent abilities, the formation of complex associations, the
+selection and encouragement of talent, and the wide diffusion and
+imitation of the accumulated products of the well-cultivated genius of
+favourably varying individuals. The fact that uneducated persons do not
+enjoy the higher tastes, and the rapidity with which such tastes are
+acquired or professed, ought to be sufficient proof that modern culture
+is brought about by far swifter and more potent influences than
+use-inheritance. Neither would this hypothetical factor of evolution
+materially aid in explaining the many other rapid changes of habit
+brought about by education, custom, and the changed conditions of
+civilization generally. Powerful tastes--as is incontestably shown in
+the cases of alcohol and tobacco--lie latent for ages, and suddenly
+become manifest when suitable conditions arise. Every discovery, and
+each step in social and moral evolution, produces its wide-spreading
+train of consequences. I see no reason why use-inheritance need be
+credited with any share in the cumulative results of the invention of
+printing and the steam-engine and gunpowder, or of freedom and security
+under representative government, or of science and art and the partial
+emancipation of the mind of man from superstition, or of the innumerable
+other improvements or changes that take place under modern civilization.
+
+Mr. Spencer suggests an inquiry whether the greater powers possessed by
+eminent musicians were not mainly due to the inherited effect of the
+musical practice of their fathers (p. 19). But these great musicians
+inherited far more than their parents possessed. The excess of their
+powers beyond their parents' must surely be attributed to spontaneous
+variation; and who shall say that the rest was in any way due to
+use-inheritance? If, too, the superiority of geniuses proves
+use-inheritance, why should not the inferiority of the sons of geniuses
+prove the existence of a tendency which is the exact opposite of
+use-inheritance? But nobody collects facts concerning the degenerate
+branches of musical families. Only the favourably varying branches are
+noticed, and a general impression of rapid evolution of talent is thus
+produced. Such cases might be explained, too, by the facts that musical
+faculty is strong in both sexes, that musical families associate
+together, and that the more gifted members may intermarry. Great
+musicians are often astonishingly precocious. Meyerbeer "played
+brilliantly" at the age of six. Mozart played beautifully at four. Are
+we to suppose that the effect of the _adult_ practice of parents was
+inherited at this early age? If use-inheritance was not necessary in the
+case of Handel, whose father was a surgeon, why is it needed to account
+for Bach?
+
+
+LACK OF EVIDENCE.
+
+The "direct proofs" of use-inheritance are not as plentiful as might be
+desired, it appears (pp. 24-28). This acknowledged "lack of recognized
+evidence" is indeed the weakest feature in the case, though Mr. Spencer
+would fain attribute this lack of direct proof to insufficient
+investigation and to the inconspicuous nature of the inheritance of the
+modification. But there is an almost endless abundance of conspicuous
+examples of the effects of use and disuse in the individual. How is it
+that the subsequent inheritance of these effects has not been more
+satisfactorily observed and investigated? Horse-breeders and others
+could profit by such a tendency, and one cannot help suspecting that the
+reason they ignore it must be its practical inefficacy, arising probably
+from its weakness, its obscurity and uncertainty or its non-existence.
+
+
+INHERITED EPILEPSY IN GUINEA-PIGS.
+
+Brown-Séquard's discovery that an epileptic tendency artificially
+produced by mutilating the nervous system of a guinea-pig is
+occasionally inherited may be a fact of "considerable weight," or on the
+other hand it may be entirely irrelevant. Cases of this kind strike one
+as peculiar exceptions rather than as examples of a general rule or law.
+They seem to show that certain morbid conditions may occasionally affect
+both the individual and the reproductive elements or transmissible type
+in a similar manner; but then we also know that such prompt and complete
+transmission of an artificial modification is widely different from the
+usual rule. Exceptional cases require exceptional explanations, and are
+scarcely good examples of the effect of a general tendency which in
+almost all other cases is so inconspicuous in its immediate effects.
+Further remarks on this inherited epilepsy can be most conveniently
+introduced later on in connection with Darwin's explanation of the
+inherited mutilation which it usually accompanies, but which Mr. Spencer
+does not mention.
+
+
+INHERITED INSANITY AND NERVOUS DISORDERS.
+
+Mr. Spencer infers that, because insanity is usually hereditary, and
+insanity can be artificially produced by various excesses, therefore
+this artificially-produced insanity must also be hereditary (p. 28).
+Direct evidence of this conclusion would be better than a mere inference
+which may beg the very question at issue. That the liability to insanity
+commonly runs in families is no proof that strictly non-inherited
+insanity will subsequently become hereditary. I think that theories
+should be based on facts rather than facts on theories, especially when
+those facts are to be the basis or proof of a further theory.
+
+Mr. Spencer also points out that he finds among physicians "the belief
+that nervous disorders of a less severe kind are inheritable"--a general
+belief which does not necessarily include the transmission of purely
+artificially-produced disorders, and so misses the point which is really
+at issue. He proceeds, however, to state more definitely that "men who
+have prostrated their nervous systems by prolonged overwork or in some
+other way, have children more or less prone to nervousness." The
+following observations will, I think, warrant at least a suspension of
+judgment concerning this particular form of use-inheritance.
+
+(1) The nervousness is seen in the _children_ at an early age, although
+the nervous prostration from which it is supposed to be derived
+obviously occurs in the parent at a much later period of life. This
+change in time is contrary to the rule of inheritance at corresponding
+periods; and, together with the unusual promptness and comparative
+completeness of the inheritance, it may indicate a special injury or
+deterioration of the reproductive elements rather than true inheritance.
+The healthy brain of early life has failed to transmit its robust
+condition. Is use-inheritance, then, only effective for evil? Does it
+only transfer the newly-acquired weakness, and not the previous
+long-continued vigour?
+
+(2) Members of nervous families would be liable to suffer from nervous
+prostration, and by the ordinary law of heredity alone would transmit
+nervousness to their children.
+
+(3) The shattered nerves or insanity resulting from alcoholic and other
+excesses, or from overwork or trouble, are evidently signs of a grave
+constitutional injury which may react upon the reproductive elements
+nourished and developed in that ruined constitution. The deterioration
+in parent and child may often display itself in the same organs--those
+probably which are hereditarily weakest. Acquired diseases or disorders
+thus appear to be transmitted, when all that was conveyed to the
+offspring was the exciting cause of a lowered vitality or disordered
+action, together with the ancestral liability to such diseases under
+such conditions.
+
+(4) Francis Galton says that "it is hard to find evidence of the power
+of the personal structure to react upon the sexual elements, that is not
+open to serious objection." Some of the cases of apparent inheritance he
+regards as coincidence of effect. Thus "the fact that a drunkard will
+often have imbecile children, although his offspring previous to his
+taking to drink were healthy," is an "instance of simultaneous action,"
+and not of true inheritance. "The alcohol pervades his tissues, and, of
+course, affects the germinal matter in the sexual elements as much as it
+does that in his own structural cells, which have led to an alteration
+in the quality of his own nerves. Exactly the same must occur in the
+case of many constitutional diseases that have been acquired by
+long-continued irregular habits."[13]
+
+
+INDIVIDUAL AND TRANSMISSIBLE TYPE NOT MODIFIED ALIKE BY THE DIRECT
+EFFECT OF CHANGED HABITS OR CONDITIONS.
+
+Mr. Spencer finds it hard to believe that the modifications conveyed to
+offspring are not identical in tendency with the changes effected in the
+parent by altered use or habit (pp. 23-25, 34). But it is perfectly
+certain that the two sets of effects do not necessarily correspond. The
+effect of changed habits or conditions on the individual is often very
+far from coinciding with the effects on the reproductive elements or
+the transmissible type. The reproductive system is "extremely
+sensitive" to very slight changes, and is often powerfully affected by
+circumstances which otherwise have little effect on the individual
+(_Origin of Species_, p. 7). Various animals and plants become sterile
+when domesticated or supplied with too much nourishment. The native
+Tasmanians have already become extinct from sterility caused by greatly
+changed diet and habits. If, as Mr. Spencer teaches, continued culture
+and brain-work will in time produce lessened fertility or comparative
+sterility, we may yet have to be careful that intellectual development
+does not become a species of suicide, and that the culture of the race
+does not mean its extinction--or at least the extinction of those most
+susceptible of culture.
+
+The reproductive elements are also disturbed and modified in innumerable
+minor ways. Changed conditions or habits tend to produce a general
+"plasticity" of type, the "indefinite variability" thus caused being
+apparently irrelevant to the change, if any, in the individual.[14] A
+vast number of variations of structure have certainly arisen
+independently of similar parental modification as the preliminary.
+Whatever first caused these "spontaneous" congenital variations affected
+the reproductive elements quite differently from the individual. "When a
+new peculiarity first appears we can never predict whether it will be
+inherited." Many varieties of plants only keep true from shoots, and not
+from seed, which is by no means acted on in the same way as the
+individual plant. Seeing that such plants have _two_ reproductive
+types, both constant, it is evident that these cannot both be modified
+in the same way as the parent is modified. Many parental modifications
+of structure and habit are certainly not conveyed to neuter ants and
+bees; other modifications, which are not seen in the parents, being
+conveyed instead. Many other circumstances tend to show that the
+individual and the transmissible type are independent of each other so
+far as modifications of parts are concerned.
+
+It may seem natural to expect the transmission of an enlarged muscle or
+a cultivated brain, but, on the other hand, why should it be
+unreasonable to expect that a modification which was non-congenital in
+origin should still remain non-congenital? Why should the
+non-transmission of that which was not transmitted be surprising?
+
+Mr. Spencer thinks that the non-transmission of acquired modifications
+is incongruous with the great fact of atavism. But the great law of the
+inheritance of that which is a development of the transmissible type
+does not necessarily imply the inheritance of modifications acquired by
+the individual. Because English children may inherit blue eyes and
+flaxen hair from their Anglo-Saxon ancestors, it by no means follows
+that an Englishman must inherit his father's sunburnt complexion or
+smooth-shaven face. Of course atavism ultimately adopts many instances
+of revolt against its sway. But to assume that these changes of type
+_follow_ the personal change rather than cause it, is to assume the
+whole question at issue. That like begets like is true as a broad
+principle, but it has many exceptions, and the non-heredity of acquired
+characters may be one of them.
+
+
+FOOTNOTES:
+
+[2] _Principles of Biology_, § 166, footnote. The English jaws are
+somewhat lighter than the Australian jaws, though I could not undertake
+to affirm that they are really shorter and smaller. In the typical
+skulls depicted on p. 68 of the official guide to the mammalian
+galleries at South Kensington, the typical Caucasian jaw is very much
+larger than the Tasmanian jaw, although the repulsively obtrusive teeth
+of the latter convey the contrary idea to the imagination. Mr. Spencer's
+assumption that the ancient Britons had large jaws appears to me
+erroneous. (See Professor Rolleston's _Scientific Papers and Addresses_,
+i. p. 250.)
+
+[3] Romanes, Galton, and Weismann have made great use of this principle
+in explaining the diminution of disused organs. Weismann has given it
+the name of _Panmixia_,--_all_ individuals being equally free to survive
+and commingle their variations, and not merely selected or favoured
+individuals. See his _Essays on Heredity_, &c., p. 90 (Clarendon Press).
+
+[4] Inclusive in each case of fixed strengthening wire weighing about a
+sixteenth of an ounce or less.
+
+[5] References of course are to _Factors of Organic Evolution_.
+
+[6] P. 13; and _Nineteenth Century_, February, 1888, p. 211.
+
+[7] Tomes's _Dental Surgery_, pp. 273-275. Tomes observes that it is as
+yet uncertain in what way civilization predisposes to caries. But he
+shows that caries is caused by the lime salts in the teeth being
+attacked by _acids_ from decomposing food in crevices, from artificial
+drink such as cyder, from sugar, from medicine, and from vitiated
+secretions of the mouth. It is evident that in civilized races natural
+selection cannot so rigorously insist on sound teeth, sound
+constitutions, and _protective alkaline_ saliva. The reaction of the
+civilized mouth is often acid, especially when the system is disordered
+by dyspepsia or other diseases or forms of ill-health common under
+civilization. The main supply of saliva, which is poured from the cheeks
+opposite the upper molars, is often acid when in small quantities. But
+the submaxillary and sub-lingual saliva poured out at the foot of the
+lower incisors and held in the front part of the jaw as in a spoon,
+"differs from parotid saliva in being more alkaline" (Foster's _Text
+Book of Physiology_, p. 238; Tomes, pp. 284, 685). One observer says
+that the reaction near the lower incisors is "never acid." Hence (I
+conclude) the remarkable immunity of the lower incisors and canines from
+decay, an immunity which extends backwards in a lessening degree to the
+first and second bicuspids. The close packing of the lower incisors may
+assist by preventing the retention of decaying fragments of food. Sexual
+selection may promote caries by favouring white teeth, which are more
+prone to decay than yellow ones. Acid vitiation of the mucus might
+account both for caries and (possibly) for the strange infertility of
+some inferior races under civilization.
+
+[8] _Origin of Species_, pp. 198-9; _Variation of Animals and Plants
+under Domestication_, vol. ii. p. 328 footnote, also p. 206.
+
+[9] Mr. Spencer weakly argues that an advantageous attribute (such as
+swiftness, keen sight, courage, sagacity, strength, &c.) cannot be
+increased by natural selection unless it is "of greater importance, for
+the time being, than most of the other attributes"; and that natural
+selection cannot develop any one superiority when animals are equally
+preserved by "other superiorities." But as natural selection will
+simultaneously eliminate tendencies to slowness, blindness, deafness,
+stupidity, &c., it _must_ favour and improve many points simultaneously,
+although no one of them may be of greater importance than the rest. Of
+course the more complicated the evolution the slower it will be; but
+time is plentiful, and the amount of elimination is correspondingly
+vast.
+
+[10] I venture to coin this concise term to signify _the direct
+inheritance of the effects of use and disuse in kind_. Having a name for
+a thing is highly convenient; it facilitates clearness and accuracy in
+reasoning, and in this particular inquiry it may save some confusion of
+thought from double or incomplete meanings in the shortened phrases
+which would otherwise have to be employed to indicate this great but
+nameless factor of evolution.
+
+[11] _Origin of Species_, pp. 230-232; Bates's _Naturalist on the
+Amazons_. Darwin is "surprised that no one has hitherto advanced the
+demonstrative case of neuter insects, against the well-known doctrine of
+inherited habit, as advanced by Lamarck." As he justly observes, "it
+proves that with animals, as with plants, any amount of modification may
+be effected by the accumulation of numerous, slight, spontaneous
+variations, which are in any way profitable, without exercise or habit
+having been brought into play. For peculiar habits confined to the
+workers or sterile females, however long they might be followed, could
+not possibly affect the males and fertile females, which alone leave any
+descendants." Some slight modification of these remarks, however, may
+possibly be needed to meet the case of "factitious queens," who
+(probably through eating particles of the royal food) become capable of
+producing a few male eggs.
+
+[12] _Descent of Man_, pp. 573, 572, and footnote.
+
+[13] _Contemporary Review_, December, 1875, p. 92.
+
+[14] See _Origin of Species_, pp. 5-8. "Changed conditions induce an
+almost indefinite amount of fluctuating variability, by which the whole
+organization is rendered in some degree plastic" (_Descent of Man_, p.
+30). It also appears that "the nature of the conditions is of
+subordinate importance in comparison with the nature of the organism in
+determining each particular form of variation;--perhaps of not more
+importance than the nature of the spark, by which a mass of combustible
+matter is ignited, has in determining the nature of the flames" (_Origin
+of Species_, p. 8).
+
+
+
+
+DARWIN'S EXAMPLES.
+
+
+The most formidable cases brought forward by Mr. Spencer are from
+Darwin. I shall endeavour to show, however, that Darwin was probably
+wrong in retaining the older explanation of these facts, and that the
+remains of the Lamarckian theory of use-inheritance need not any longer
+encumber the great explanation which has superseded that fallacious and
+unproven theory and has rendered it totally unnecessary. Meanwhile I
+think it is an excellent sign that Mr. Spencer has to complain that
+"Nowadays most naturalists are more Darwinian than Mr. Darwin
+himself"--inasmuch as they are inclined to say that there is "no proof"
+that the effects of use and disuse are inherited. Other excellent signs
+are the recent issue of a translation of Weismann's important essays on
+this and kindred subjects,[15] the strong support given to his views by
+Wallace in his _Darwinism_, and their adoption by Ray Lankester in his
+article on Zoology in the latest edition of the _Encyclopędia
+Britannica_. So sound and cautious an investigator as Francis Galton had
+also in 1875 concluded that "acquired modifications are barely, if at
+all, _inherited_, in the correct sense of that word."
+
+Darwin's belief in the inheritance of acquired characters was more or
+less hereditary in the family. His grandfather, Erasmus Darwin,
+anticipated Lamarck's views in his _Zoonomia_, which Darwin at one time
+"greatly admired." His father was "convinced" of the "inherited evil
+effects of alcohol," and to this extent at least he strongly impressed
+the belief in the inheritance of acquired characters upon his
+children's minds.[16] Darwin must also have been imbued with Lamarckian
+ideas from other sources, although Dr. Grant's enthusiastic advocacy
+entirely failed to convert him to a belief in evolution.[17]
+"Nevertheless," he says, "it is probable that the hearing rather early
+in life such views maintained and praised may have favoured my upholding
+them under a different form in my _Origin of Species_"--a remark which
+refers to Lamarck's views on the general doctrine of evolution, but
+might also prove equally true if applied to Darwin's partial retention
+of the Lamarckian explanation of that evolution. Professor Huxley has
+pointed out that in Darwin's earlier sketch of his theory of evolution
+(1844) he attached more weight to the inheritance of acquired habits
+than he does in his _Origin of Species_ published fifteen years
+later.[18] He appears to have acquired the belief in early life without
+first questioning and rigorously testing it as he would have done had it
+originated with himself. In later life it appeared to assist his theory
+of evolution in minor points, and in particular it appeared absolutely
+indispensable to him as the _only_ explanation of the diminution of
+disused parts in cases where, as in domestic animals, economy of growth
+seemed to be practically powerless. He failed to adequately notice the
+effect of panmixia, or the withdrawal of selection, in causing or
+allowing degeneracy and dwindling under disuse; and he hardly attached
+sufficient importance to the fact that rudimentary organs and other
+supposed effects of use or disuse are quite as marked features in
+neuter insects which cannot transmit the effects of use and disuse as
+they are in the higher animals.
+
+
+REDUCED WINGS OF BIRDS OF OCEANIC ISLANDS.
+
+Darwin himself has pointed out that the rudimentary wings of island
+beetles, at first thought to be due to disuse, are mainly brought about
+by natural selection--the best-winged beetles being most liable to be
+blown out to sea. But he says that in birds of the oceanic islands "not
+persecuted by any enemies, the reduction of their wings has probably
+been caused by disuse." This explanation may be as fallacious as it is
+acknowledged to have been in the case of the island beetles. According
+to Darwin's own views, natural selection _must_ at least have played an
+important part in reducing the wings; for he holds that "natural
+selection is continually trying to economize every part of the
+organization." He says: "If under changed conditions of life a
+structure, before useful, becomes less useful, its diminution will be
+favoured, for it will profit the individual not to have its nutriment
+wasted in building up an useless structure.... Thus, as I believe,
+natural selection will tend in the long run to reduce any part of the
+organization, as soon as it becomes, through changed habits,
+superfluous."[19] If, as Darwin powerfully urges (and he here ignores
+his usual explanation), ostriches' wings are insufficient for flight in
+consequence of the economy enforced by natural selection,[20] why may
+not the reduced wings of the dodo, or the penguin, or the apteryx, or of
+the Cursores generally, be wholly attributed to natural selection in
+favour of economy of material and adaptation of parts to changed
+conditions? The great principle of economy is continually at work
+shaping organisms, as sculptors shape statues, by removing the
+superfluous parts; and a mere glance at the forms of animals in general
+will show that it is well-nigh as dominant and universal a principle as
+is that of the positive development of useful parts. Other causes,
+moreover besides actual economy, would favour shorter and more
+convenient wings on oceanic islands. In the first place, birds that were
+somewhat weak on the wing would be most likely to settle on an island
+and stay there. Shortened wings would then become advantageous because
+they would restrain fatal migratory tendencies or useless and perilous
+flights in which the birds that flew furthest would be most often
+carried away by storms and adverse winds. Reduced wings would keep the
+birds near the shelter and the food afforded by the island and its
+neighbourhood, and in some cases would become adapted to act as fins or
+flappers for swimming under water in pursuit of fish.
+
+The reduced size of the wings of these island birds is paralleled by the
+remarkable thinness, &c., of the shell of the "gigantic land-tortoise"
+of the Galapagos Islands. The changes seen in the carapace can hardly
+have been brought about by the inherited effects of special disuse. Why
+then should not the reduction of equally useless, more wasteful, and
+perhaps positively dangerous wings be also due to an economy which has
+become advantageous to bird and reptile alike through the absence of the
+mammalian rivals whose places they are evidently being modified to fill?
+The _complete_ loss of the wings in neuter ants and termites can
+scarcely be due to the inherited effects of disuse; and as natural
+selection has abolished these wings in spite of the opposition of
+use-inheritance, it must clearly be fully competent to reduce wings
+without its aid. In considering the rudimentary wings of the apteryx,
+or of the moa, emu, ostrich, &c., we must not forget the frequent or
+occasional occurrence of hard seasons, and times of drought and famine,
+when Nature eliminates redundant, wasteful, and ill-adapted organisms in
+so severe and wholesale a fashion. Where enemies are absent there would
+be unrestrained multiplication, and this would greatly increase the
+severity of the competition for food, and so hasten the elimination of
+disused and useless parts.
+
+
+DROOPING EARS AND DETERIORATED INSTINCTS.
+
+Mr. Galton has pointed out that existing races and existing organs are
+only kept at their present high pitch of organic excellence by the
+stringent and incessant action of natural or artificial selection; and
+the simple relaxation or withdrawal of such selective influences will
+almost necessarily result in a certain amount of deterioration,
+independently even of the principle of economy.[21] I think that this
+cessation of a previous selective process will account for the
+drooping--but _not diminished_--ears of various domesticated animals
+(human preference and increased weight evidently aiding), and also for
+the inferior instincts seen in them and in artificially-fed caterpillars
+of the silk-moth, which now "often commit the strange mistake of
+devouring the base of the leaf on which they are feeding, and
+consequently fall down." Anyhow, I fail to see that anything is proved
+by this latter case, except that natural instinct may be perverted or
+aborted under unnatural conditions and a changed method of selection
+which abolishes the powerful corrective formerly supplied by natural
+selection.
+
+
+WINGS AND LEGS OF DUCKS AND FOWLS.
+
+The reduced wings and enlarged legs of domesticated ducks and fowls are
+attributed by Darwin and Spencer to the inheritance of the effects of
+use and disuse. But the inference by no means follows. Natural selection
+would usually favour these adaptive changes, and they would also have
+been aided by an artificial selection which is often unconscious or
+indirect. Birds with diminished power of flight would be less difficult
+to keep and manage, and in preserving and multiplying such birds man
+would be unconsciously bringing about structural changes which would
+easily be regarded as effects of use and disuse. "About eighteen
+centuries ago Columella and Varro speak of the necessity of keeping
+ducks in netted enclosures like other wild fowl, so that at this period
+there was danger of their flying away."[22] Is it not probable that the
+best fliers would escape most frequently, or would pine most if kept
+confined? On the other hand, birds with lessened powers of flight would
+not be eliminated as under natural conditions, but would be favoured;
+and natural selection, together with artificial selection of the most
+flourishing birds, would thicken and strengthen the legs to meet
+increased demands upon them.
+
+The diminution of the duck's wing is not great even in the birds that
+"never fly," and from this we must deduct the direct effect of disuse on
+the individual during its lifetime. As Weismann suggests, the
+_inherited_ portion of the change could only be ascertained by comparing
+the bones, &c., of wild and tame ducks _similarly reared_. If individual
+disuse diminished the weight of the duck's wing-bones by 9 per cent.
+there would be nothing left to account for.
+
+I suspect that investigation would reveal anomalies inconsistent with
+the theory of use-inheritance. Thus according to Darwin's tables of
+comparative weights and measurements[23] the leg-bones of the Penguin
+duck have slightly diminished in length, although they have increased 39
+per cent. in weight. Relatively to the weight of the skeleton, the
+leg-bones have shortened in the tame breeds of ducks by over 5 per cent.
+(and in two breeds by over 8 per cent.) although they have increased
+more than 28 per cent. in proportional weight.[24] How can increased use
+simultaneously shorten and thicken these bones? If the relative
+shortening is attributed to a heavier skeleton, then the apparently
+reduced weight of the wing-bones is fully accounted for by the same
+circumstance, and disuse has had no inherited effect.
+
+Another strange circumstance is that the wing-bones have diminished _in
+length only_. The shortening is about 6 per cent. more than in the
+shortened legs, and it amounts to 11 per cent. as compared with the
+weight of the skeleton. Such a shortening should represent a reduction
+of 29 per cent. in weight, whereas the actual reduction in the weight of
+the wing-bones relatively to the weight of the skeleton is only 9 per
+cent. even in the breeds that never fly. Independently of shortening,
+the disused wing-bones have actually thickened or increased in weight.
+In the Aylesbury duck the disproportion caused by these conflicting
+changes is so great that the wing-bones are 47 per cent. heavier than
+they should be if their weight had varied proportionally with their
+length.[25] The reduction in weight on which Darwin relies seems to be
+entirely due to the shortening, and this shortening appears to be
+irrelevant to disuse, since the wings of the Call duck are similarly
+shortened in their proportions by 12 per cent., although this bird
+habitually flies to such an extent that Darwin partly attributes the
+greatly increased weight of its wing-bones to increased use under
+domestication.
+
+We find that _all_ the changes are in the direction of shorter and
+thicker bones--a tendency which must be largely dependent upon the
+suspension of the rigorous elimination which keeps the bones of the
+wild duck _long and light_. The used leg-bones and the disused
+wing-bones have alike been shortened and thickened, though in different
+proportions. Natural or artificial selection might easily thicken legs
+without lengthening them, or shorten wings without eliminating strong
+heavy bones, but it can hardly be contended that use-inheritance has
+acted in such conflicting ways. The thickening of the wing-bones has
+actually more than kept pace with any increase of weight in the
+skeleton, in spite of the effect of individual disuse and of the alleged
+cumulative effect of ancestral disuse for hundreds of generations. The
+case of the duck deserves special attention as a crucial one, if only
+from the fact that in this instance, and in this instance only, has
+Darwin given the weights of the skeletons, thus furnishing the means for
+a closer examination of his details than is usually possible.
+
+If we ignore such factors as selection, panmixia, correlation, and the
+effects of use and disuse during lifetime, and still regard the case of
+the domestic duck as a valid proof of the inheritance of the effects of
+use and disuse, we must also accept it as an equally valid proof that
+the effects of use and disuse are _not_ inherited. Nay, we may even have
+to admit that, in two points out of four, the _inherited_ effect of use
+and disuse on successive generations is exactly opposite to the
+immediate effect on the individual.
+
+Among fowls the wing-bones have lost much in weight but little or
+nothing in length--which is the reverse of what has occurred in ducks,
+although disuse is alleged to be the common cause in both cases. Some of
+the fowls which fly least have their wing-bones as long as ever. In the
+case of the Silk and Frizzled fowls--ancient breeds which "cannot fly at
+all"--and in that of the Cochins, which "can hardly fly up to a low
+perch," Darwin observes "how truly the proportions of an organ may be
+inherited although not fully exercised during many generations."[26] In
+four out of twelve breeds the wing-bones had become slightly heavier
+relatively to the leg-bones. Do not these facts tend to show that the
+changes in fowls' wings are due to fluctuating variability and selective
+influences rather than to a general law whereby the effects of disuse
+are cumulatively inherited?
+
+
+PIGEONS' WINGS.
+
+Concerning pigeons' wings Darwin says: "As fancy pigeons are generally
+confined in aviaries of moderate size, and as even when not confined
+they do not search for their own food, they must during many generations
+have used their wings incomparably less than the wild rock-pigeon ...
+but when we turn to the wings we find what at first appears a wholly
+different and unexpected result."[27] This unexpected increase in the
+spread of the wings from tip to tip is due to the feathers, which have
+lengthened in spite of disuse. Excluding the feathers, the wings were
+shorter in seventeen instances, and longer in eight. But as artificial
+selection has lengthened the wings in some instances, why may it not
+have shortened them in others? Wings with shortened bones would fold up
+more neatly than the long wings of the Carrier pigeon for instance, and
+so might unconsciously be favoured by fanciers. The selection of elegant
+birds with longer necks or bodies would cause a relative reduction in
+the wings--as with the Pouter, where the wings have been greatly
+lengthened but not so much as the body.[28] Slender bodies, too, and the
+lessened divergence of the furculum,[29] would slightly diminish the
+spread of the wings, and so would affect the measurements taken. As the
+wing-bones, moreover, are to some extent correlated with the beak and
+the feet, the artificial selection of shortened beaks might tend to
+shorten the wing as well as the feet. Under these circumstances how can
+we be sure of the actual efficacy of use-inheritance? Surely selection
+is as fully competent to effect slight changes in the direction of
+use-inheritance as it undoubtedly is to effect great changes in direct
+opposition to that alleged factor of evolution.
+
+
+SHORTENED BREAST-BONE IN PIGEONS.
+
+The shortening of the sternum in pigeons is attributed to disuse of the
+flight muscles attached to it. The bone is only shortened by a third of
+an inch, but this represents a very remarkable reduction in proportional
+length, which Darwin estimates at from one-seventh to one-eighth, or
+over 13 per cent. This marked reduction, too, quite unlike the slight
+reduction of the wing-bones to which the other ends of the muscles are
+attached, was universal in the eleven specimens measured by Darwin; and
+the bone, though acknowledged to have been modified by artificial
+selection in some breeds, is not so open to observation as wings or
+legs. Even, however, if this relative shortening of the sternum remained
+otherwise inexplicable, it might still be as irrelevant to use and
+disuse as is the fact that "many breeds" of fancy pigeons have lost a
+rib, having only seven where the ancestral rock-pigeon has eight.[30]
+But the excessive reduction in the sternum is far from being
+inexplicable. In the first place Darwin has somewhat over-estimated it.
+Instead of comparing the deficiency of length with the increased length
+which _should_ have been acquired (since the pigeons have increased in
+average size) he compares it with the length of the breast-bone in the
+rock-pigeon.[31] By this method if a pigeon had doubled in dimensions
+while its breast-bone remained unaltered, the reduction would be put
+down as 100 per cent., whereas obviously the true reduction would be
+one-half, or 50 per cent. of what the bone _should be_. Avoiding this
+error and a minor fallacy besides, a sound estimate reduces the supposed
+reduction of 13 or 14 per cent. to one of 11·7 per cent., which is still
+of course a considerable diminution.
+
+Part of this reduction must be due to the direct effect of disuse during
+the lifetime of the individual. Another and perhaps very considerable
+part of the relative change must be attributed to the lengthening of the
+neck or body by artificial selection, or to other modifications of
+shape and proportion effected directly or indirectly by the same
+cause.[32] The reduction is greatest in the Pouter (18-1/2 per cent.)
+and in the Pied Scanderoon (17-1/2 per cent.). In the former the body
+has been greatly elongated by artificial selection and three or four
+additional vertebrę have been acquired in the hinder part of the
+body.[33] In the latter a long neck increases the length of the bird,
+and so causes, or helps to cause, the relative shortening of the
+breast-bone. In the English Carrier--which experiences the effects of
+disuse, as it is too valuable to be flown--the relative reduction of 11
+per cent. is apparently more than accounted for by the "elongated
+neck." The Dragon also has a long neck. In the Pouter, although the
+breast-bone has been shortened by 18-1/2 per cent. relatively to the
+length of the body, it has _lengthened_ by 20 per cent. relatively to
+the _bulk_ of the body.[34] Darwin forgot to ask whether allowance must
+not be made for a frequent, or perhaps general, elongation of the neck
+and the hinder part of the body, and the relative shortening or the
+throwing forward of the central portion containing the ribs (frequently
+one less in number) and the sternum. The whole body of the pigeon is so
+much under the control of artificial selection, that every precaution
+must be taken to guard against such possible sources of error.[35]
+
+Under domestication there would be a suspension of the previous
+elimination of reduced breast-bones by natural selection (Weismann's
+panmixia), and a diminution of the parts concerned in flying might even
+be favoured, as lessened powers of _continuous_ flight would prevent
+pigeons from straying too far, and would fit them for domestication or
+confinement. Such causes might reduce some of the less observed parts
+affected by flying, while still leaving the wing of full size for
+occasional flight, or to suit the requirements of the pigeon-fanciers. A
+change might thus be commenced like that seen in the rudimentary keel of
+the sternum in the owl-parrot of New Zealand, which has lost the power
+of flight although still retaining fairly-developed wings.
+
+
+SHORTENED FEET IN PIGEONS.
+
+Darwin thinks it highly probable that the short feet of most breeds of
+pigeons are due to lessened use, though he owns that the effects of
+correlation with the shortened beak are more plainly shown than the
+effects of disuse.[36] But why need the inherited effects of disuse be
+called in to explain an average reduction of some 5 per cent., when
+Darwin's measurements show that in the breeds where long beaks are
+favoured the principle of correlation between these parts has lengthened
+the foot by 13 per cent. in spite of disuse?
+
+
+SHORTENED LEGS OF RABBITS.
+
+In the case of the domestic rabbit Darwin notices that the bones of the
+legs have (relatively) become shorter by an inch and a half. But as the
+leg-bones have _not_ diminished in relative weight,[37] they must
+clearly have grown _thicker_ or denser. If disuse has shortened them, as
+Darwin supposes, why has it also thickened them? The ears and the tail
+have been lengthened in spite of disuse. Why then may not the ungainly
+hind-legs have been shortened by human preference independently of the
+inherited effects of disuse? By relying on apparently favourable
+instances and neglecting the others it would be easy to arrive at all
+manner of unsound conclusions. We might thus become convinced that
+vessels tend to sail northwards, or that a pendulum oscillates more
+often in one direction than in the other. It must not be forgotten that
+it would be easy to cite an enormous number of cases which are in direct
+conflict with the supposed law of use-inheritance.
+
+
+BLIND CAVE-ANIMALS.
+
+Weak or defective eyesight is by no means rare as a spontaneous
+variation in animals, "the great French veterinary Huzard going so far
+as to say that a blind race [of horses] could soon be formed." Natural
+selection evolves blind races whenever eyes are useless or
+disadvantageous, as with parasites. This may apparently be done
+independently of the effects of disuse, for certain neuter ants have
+eyes which are reduced to a more or less rudimentary condition, and
+neuter termites are blind as well as wingless. In one species of ant
+(_Eciton vastator_) the sockets have disappeared as well as the eyes. In
+deep caves not only would natural selection cease to maintain good
+eyesight but it would persistently favour blindness--or the entire
+removal of the eye when greatly exposed, as in the cave-crab--and as Dr.
+Ray Lankester has indicated,[38] there would have been a previous
+selection of animals which through spontaneous weakness, sensitiveness,
+or other affection of the eye found refuge and preservation in the cave,
+and a subsequent selection of the descendants whose fitness for relative
+darkness led them deeper into the cave or prevented them from straying
+back to the light with its various dangers and severer competition.
+Panmixia, however, as Weismann has shown, would probably be the most
+important factor in causing blindness.
+
+
+INHERITED HABITS.
+
+Darwin says: "A horse is trained to certain paces, and the colt inherits
+similar consensual movements."[39] But selection of the constitutional
+tendency to these paces, and imitation of the mother by the colt, may
+have been the real causes. The evidence, to be satisfactory, should show
+that such influences were excluded. Men acquire proficiency in swimming,
+waltzing, walking, smoking, languages, handicrafts, religious beliefs,
+&c., but the children only appear to inherit the innate abilities or
+constitutional proclivities of their parents. Even the songs of birds,
+including their call-notes, are no more inherited than is language by
+man (_Descent of Man_, p. 86). They are learned from the parent.
+Nestlings which acquire the song of a distinct species, "teach and
+transmit their new song to their offspring." If use-inheritance has not
+fixed the song of birds, why should we suppose that in a single
+generation it has transmitted a newly-taught method of walking or
+trotting?
+
+It is alleged that dogs inherit the intelligence acquired by association
+with man, and that retrievers inherit the effects of their
+training.[40] But selection and imitation are so potent that the
+additional hypothesis of use-inheritance seems perfectly superfluous.
+Where intelligence is not highly valued and carefully promoted by
+selection, the intelligence derivable from association with man does
+_not_ appear to be inherited. Lap-dogs, for instance, are often
+remarkably stupid.
+
+Darwin also instances the inheritance of dexterity in seal-catching as a
+case of use-inheritance.[41] But this is amply explained by the ordinary
+law of heredity. All that is needed is that the son shall inherit the
+suitable faculties which the father inherited before him.
+
+
+TAMENESS OF RABBITS.
+
+Darwin holds that in some cases selection alone has modified the
+instincts and dispositions of domesticated animals, but that in most
+cases selection and the inheritance of acquired habits have concurred in
+effecting the change. "On the other hand," he says, "habit alone in some
+cases has sufficed; hardly any animal is more difficult to tame than the
+young of the wild rabbit; scarcely any animal is tamer than the young of
+the tame rabbit; but I can hardly suppose that domestic rabbits have
+often been selected for tameness alone; so that we must attribute at
+least the greater part of the inherited change from extreme wildness to
+extreme tameness to habit and long-continued close confinement."[42]
+
+But there are strong, and to me irresistible, arguments to the contrary.
+I think that the following considerations will show that the greater
+part, if not the whole, of the change must be attributed to selection
+rather than to the direct inheritance of acquired habit.
+
+(1) For a period which may cover thousands of generations, there has
+been an entire cessation of the natural selection which maintains the
+wildness (or excessive fear, caution, activity, &c.) so indispensably
+essential for preserving defenceless wild rabbits of all ages from the
+many enemies that prey upon them.
+
+(2) During this same extensive period of time man has usually killed off
+the wildest and bred from the tamest and most manageable. To some extent
+he has done this consciously. "It is very conducive to successful
+breeding to keep only such as are quiet and tractable," says an
+authority on rabbits,[43] and he enjoins the selection of the
+handsomest and _best-tempered_ does to serve as breeders. To a still
+greater extent man has favoured tameness unconsciously and indirectly.
+He has systematically selected the largest and most prolific animals,
+and has thus doubled the size and the fertility of the domestic rabbit.
+In consciously selecting the largest and most flourishing individuals
+and the best and most prolific mothers, he _must_ have unconsciously
+selected those rabbits whose relative _tameness_ or placidity of
+disposition rendered it possible for them to flourish and to produce and
+rear large and thriving families, instead of fretting and pining as the
+wilder captives would do. When we consider how exceedingly delicate and
+easily disturbed yet all-important a function is that of maternity in
+the continually breeding rabbit, we see that the tamest and the least
+terrified would be the most successful mothers, and so would continually
+be selected, although man cared nothing for the tameness in itself. The
+tamest mothers would also be less liable to neglect or devour their
+offspring, as rabbits commonly do when their young are handled too soon,
+or even when merely frightened by mice, &c., or disturbed by changed
+surroundings.
+
+(3) We must remember the extraordinary fecundity of the rabbit and the
+excessive amount of elimination that consequently takes place either
+naturally or artificially. Where nature preserved only the wildest, man
+has preserved the tamest. If there is any truth in the Darwinian theory,
+this thorough and long-continued reversal of the selective process
+_must_ have had a powerful effect. Why should it not be amply sufficient
+to account for the tameness and mental degeneracy of the rabbit without
+the aid of a factor which can readily be shown to be far weaker in its
+normal action than either natural or artificial selection? Why may not
+the tameness of the rabbit be transferred to the group of cases in
+which Darwin holds that "habit has done nothing," and selection has done
+all?
+
+(4) If use-inheritance has tamed the rabbit, why are the bucks still so
+mischievous and unruly? Why is the Angora breed the only one in which
+the males show no desire to destroy the young? Why, too, should
+use-inheritance be so much more powerful in the rabbit than with other
+animals which are far more easily tamed in the first instance? Wild
+young rabbits when domesticated "remain unconquerably wild," and,
+although they may be kept alive, they pine and "rarely come to any
+good." Yet the animal which _acquires_ least tameness--or apparently,
+indeed, none at all--inherits most! It appears, in fact, to inherit that
+which it cannot acquire--a circumstance which indicates the selection of
+spontaneous variations rather than the inheritance of changed habits.
+Such variations occasionally occur in animals in a marked degree. Of a
+litter of wolf-cubs, all brought up in the same way, "one became tame
+and gentle like a dog, while the others preserved their natural
+savagery." Is it not probable that permanent domestication was rendered
+possible by the inevitable selection of spontaneous variations in this
+direction? The _excessive_ tameness, too, of the young rabbit, while
+easily explicable as a result of unconscious selection, is not easily
+explained as a result of acquired habit. No particular care is taken to
+tame or teach or domesticate rabbits. They are bred for food, or for
+profit or appearance, and they are left to themselves most of their
+time. As Sir J. Sebright notices with some surprise, the domestic rabbit
+"is not often visited, and seldom handled, and yet it is always tame."
+
+
+MODIFICATIONS OBVIOUSLY ATTRIBUTABLE TO SELECTION.
+
+Innumerable modifications in accordance with altered use or disuse, such
+as the enlarged udders of cows and goats, and the diminished lungs and
+livers in highly bred animals that take little exercise, can be readily
+and fully explained as depending on selection. As the fittest for the
+natural or artificial requirements will be favoured, natural or
+artificial selection may easily enlarge organs that are increasingly
+used and economize in those that are less needed. I therefore see no
+necessity whatever for calling in the aid of use-inheritance as Darwin
+does, to account for enlarged udders, or diminished lungs, or the thick
+arms and thin legs of canoe Indians, or the enlarged chests of
+mountaineers, or the diminished eyes of moles, or the lost feet of
+certain beetles, or the reduced wings of logger-headed ducks, or the
+prehensile tails of monkeys, or the displaced eyes of soles, or the
+altered number of teeth in plaice, or the increased fertility of
+domesticated animals, or the shortened legs and snouts of pigs, or the
+shortened intestines of tame rabbits, or the lengthened intestines of
+domestic cats, &c.[44] Changed habits and the requisite change of
+structure will usually be favoured by natural selection; for habit, as
+Darwin says, "almost implies that some benefit great or small is thus
+derived."
+
+
+SIMILAR EFFECTS OF NATURAL SELECTION AND USE-INHERITANCE.
+
+Here we perceive a difficulty which will equally trouble those who
+affirm use-inheritance and those who deny. Broadly speaking, the
+adaptive effects ascribed to use-inheritance coincide with the effects
+of natural selection. The individual adaptability (as shown in the
+thickening of skin, fur, muscle, &c., under the stimulus of friction,
+cold, use, &c.) is identical in kind and direction with the racial
+adaptability under natural selection. Consequently the alleged
+inheritance of the advantageous effects of use and disuse cannot readily
+be distinguished from the similarly beneficial effects of natural
+selection. The indisputable fact that natural selection imitates or
+simulates the beneficial effects ascribed to use-inheritance may be the
+chief source and explanation of a belief which may prove to be
+thoroughly fallacious. A similar simulation of course occurs under
+domestication, where natural selection is partly replaced by artificial
+selection of the best adapted and therefore most flourishing animals,
+while in disused parts panmixia or the comparative cessation of
+selection will aid or replace "economy of growth" in causing
+diminution.[45]
+
+
+INFERIORITY OF SENSES IN EUROPEANS.
+
+"The inferiority of Europeans, in comparison with savages, in eyesight
+and in the other senses," is attributed to "the accumulated and
+transmitted effect of lessened use during many generations."[46] But why
+may we not attribute it to the slackened and diverted action of the
+natural selection which keeps the senses so keen in some savage races?
+
+
+SHORT-SIGHT IN WATCHMAKERS AND ENGRAVERS.
+
+Darwin notices that watchmakers and engravers are liable to be
+short-sighted, and that short-sight and long-sight certainly tend to be
+inherited.[47] But we must be careful not to beg the question at issue
+by assuming that the frequent heredity of short sight necessarily covers
+the heredity of artificially-produced short-sight. Elsewhere, however,
+Darwin states more decisively that "there is ground for believing that
+it may often originate in causes acting on the individual affected, and
+may thence-forward become transmissible."[48] This impression may arise
+(1) from the facts of ordinary heredity--the ancestral liability being
+excited in father and son by similar artificial habits, such as reading,
+and viewing objects closely as among watchmakers and engravers--or by
+constitutional deterioration from indoor life, &c., acting upon a
+constitutional liability of the eye to the "something like inflammation
+of the coats, under which they yield" and so cause shortness of sight
+by altering the spherical shape of the eye-ball. (2) Panmixia, or the
+suspension of natural selection, together with altered habits, will
+account for an increase of short-sight among the population generally.
+(3) Long-sighted people could not work at watchmaking and engraving so
+comfortably and advantageously as at other occupations, and hence would
+be less likely to take to such callings.
+
+
+LARGER HANDS OF LABOURERS' INFANTS.[49]
+
+These are best explained as the result of natural selection and of the
+diminution of the hand by sexual selection in the gentry. If the larger
+hands of labourers' infants are really due to the inherited effects of
+ancestral use, why does the development occur so early in life, instead
+of only at a corresponding period, as is the rule? During the first few
+years of its life, at least, the labourer's infant does no more work
+than the gentleman's child. Why are not the effects of this disuse
+inherited by the labourer's infant? If the enlargement of the infant's
+hand illustrates the transference of a character gained later in life,
+it is evident that the transference must take place in spite of the
+inherited effects of disuse.
+
+
+THICKENED SOLE IN INFANTS.
+
+Darwin also attributes the thickened sole in infants, "long before
+birth," to "the inherited effects of pressure during a long series of
+generations."[50] But disuse should make the infant's sole _thin_, and
+it is this thinness that should be inherited. If we suppose the
+inheritance of the thickened soles of later life to be transferred to an
+earlier period, we have the anomaly of the inherited effects of disuse
+at that earlier period being overpowered by the untimely inheritance of
+the effects of use at another. On the other hand, it is clear that
+natural selection would favour thickened soles for walking on, and might
+also promote an early development which would ensure their being ready
+in good time for actual use; for variations in the direction of delay
+would be cut off, while variations in the other direction would be
+preserved. Anyhow, the mere transference of a character to an earlier
+period is no proof of use-inheritance. The real question is whether the
+thickened sole was gained by natural selection or by the inherited
+effects of pressure, and the mere transference or hastened appearance of
+the thickening does not in any degree solve this question. It merely
+excludes the effect of disuse during lifetime, and thus presents a
+fallacious appearance of being decisive. The thickened sole of the
+unborn infant, however, like the lanugo or hairy covering, is probably a
+result of the direct inheritance of ancestral stages of evolution, of
+which the embryo presents a condensed epitome. While the relative
+thinness of the infant's sole might be pointed to as the effect of
+_disuse_ during a long series of generations, its thickness is rather an
+illustration of atavism still resisting the effects of long-continued
+disuse. There is nothing to show that the inheritable portion of the
+full original thickness was not gained by natural selection rather than
+by the directly inherited effect of use; and the latter, being
+cumulative and indiscriminative in its action, would apparently have
+made the sole very much thicker and harder than it is. If natural
+selection were not supreme in such cases, how could we account for the
+effects of pressure resulting in hard hoofs in some cases and only soft
+pads in others?
+
+
+A SOURCE OF MENTAL CONFUSION.
+
+Of course in a certain sense this thickening of the sole has resulted
+from use. In one sense or other, most--or perhaps all--of the results of
+natural selection are inherited effects of use or disuse. Natural
+selection preserves that which is of use and which is used, while it
+eliminates that which is useless and is not used. The most confident
+assertions of the effects of use and disuse in modifying the heritable
+type, appear to rest on this indefeasible basis. Darwin's statements
+concerning the effects of use and disuse in evolution can frequently be
+read in two senses. They often command assent as undeniable truisms as
+they stand, but are of course written in another and more debatable
+sense. Thus in the case of the shortened wings and thickened legs of the
+domestic duck, I believe equally with Darwin and Spencer that "no one
+will dispute that they have resulted from the lessened use of the wings
+and the increased use of the legs." "Use" is at bottom the determining
+circumstance in evolution generally. The trunk of the elephant, the fin
+of the fish, the wing of the bird, the cunning hand of man and his
+complicated brain--and, in short, all organs and faculties
+whatsoever--can only have been moulded and developed by use--by
+usefulness and by using--but not necessarily by use-inheritance, not
+necessarily by directly inherited effects of use or disuse of parts in
+the individual. So, too, reduced or rudimentary organs are due to
+disuse, but it by no means follows that the diminution is caused by any
+direct tendency to the inheritance of the effects of disuse in the
+individual. The effects of natural selection are commonly expressible as
+effects of use and disuse, just as adaptation in nature is expressible
+in the language of teleology. But use-inheritance is no more proven by
+one of these necessary coincidences than special design is by the
+other. The inevitable simulation of use-inheritance may be entirely
+deceptive.
+
+Darwin thinks that "there can be no doubt that use in our domestic
+animals has strengthened and enlarged certain parts, and disuse
+diminished them; and that such modifications are inherited." Undoubtedly
+"such" or _similar_ modifications have often been inherited, but how can
+Darwin possibly tell that they are not due to the simulation of
+use-inheritance by natural or artificial selection acting upon general
+variability? Of the inevitability of selection and of its generally
+adaptive tendencies "there can be no doubt," and panmixia would tend to
+reduce disused parts; so that there _must always_ remain grave doubts of
+the alleged inheritance of the similar effects of use and disuse, unless
+we can accomplish the extremely difficult feat of excluding both natural
+and artificial selection as causes of enlargement, and panmixia and
+selection as causes of dwindling.
+
+
+WEAKNESS OF USE-INHERITANCE.
+
+Use-inheritance is normally so weak that it appears to be quite helpless
+when opposed to any other factor of evolution. Natural selection evolves
+and maintains the instincts of ants and termites in spite of
+use-inheritance to a more wonderful degree than it evolves the instincts
+of almost any other animal with the fullest help of use-inheritance. It
+develops seldom-used horns or natural armour just as readily as
+constantly-used hoofs or teeth. Sexual selection evolves elaborate
+structures like the peacock's tail in spite of disuse and natural
+selection combined. Artificial selection appears to enlarge or diminish
+used parts or disused parts with equal facility. The assistance of
+use-inheritance seems to be as unnecessary as its opposition is
+ineffective.
+
+The alleged inheritance of the effects of use and disuse in our domestic
+animals must be very slow and slight.[51] Darwin tells us that "there
+is no good evidence that this ever follows in the course of a single
+generation." "Several generations must be subjected to changed habits
+for any appreciable result."[52] What does this mean? One of two things.
+Either the tendency is very weak, or it is non-existent. If it is so
+weak that we cannot detect its alleged effects till several generations
+have elapsed, during which time the more powerful agency of selection
+has been at work, how are we to distinguish the effects of the minor
+factor from that of the major? Are we to conclude that use-inheritance
+_plus_ selection will modify races, just as Voltaire firmly held that
+incantations, together with sufficient arsenic, would destroy flocks of
+sheep? Is it not a significant fact that the alleged instances of
+use-inheritance so often prove to be self-conflicting in their details?
+
+For satisfactory proof of the prevalence of a law of use-inheritance we
+require normal instances where selection is clearly inadequate to
+produce the change, or where it is scarcely allowed time or opportunity
+to act, as in the immediate offspring of the modified individual. Of the
+first kind of cases there seems to be a plentiful lack. Of the latter
+kind, according to Darwin, there appears to be none--a circumstance
+which contrasts strangely and suspiciously with the many decisive cases
+in which variation from unknown causes has been inherited most
+strikingly in the immediate offspring. It must be expected, indeed, that
+among these innumerable cases some will accidentally mimic the alleged
+effects of use-inheritance.
+
+If Darwin had felt certain that the effects of habit or use tended in
+any marked degree to be conveyed directly and cumulatively to succeeding
+generations, he could hardly have given us such cautious, half-hearted
+encouragement of good habits as the following:--"It is not improbable
+that after long practice virtuous tendencies may be inherited." "Habits,
+moreover followed during many generations probably tend to be
+inherited."[53] This is probable, independently of use-inheritance. The
+"many generations" specified or implied, will allow time for the play of
+selective as well as of cumulatively-educative influences. There must
+apparently be a constitutional or inheritable predisposition or fitness
+for the habits spoken of, which otherwise would scarcely be continued
+for many generations, except by the favourably-varying branches of a
+family: which again is selection rather than use-inheritance.
+
+Where is the necessity for even the remains of the Lamarckian doctrine
+of inherited habit? Seeing how powerful the general principle of
+selection has shown itself in cases where use-inheritance could have
+given no aid or must even have offered its most strenuous opposition,
+why should it not equally be able to develop used organs or repress
+disused organs or faculties without the assistance of a relatively weak
+ally? Selection evolved the remarkable protective coverings of the
+armadillo, turtle, crocodile, porcupine, hedgehog, &c.; it formed alike
+the rose and its thorn, the nut and its shell; it developed the
+peacock's tail and the deer's antlers, the protective mimicry of various
+insects and butterflies, and the wonderful instincts of the white ants;
+it gave the serpent its deadly poison and the violet its grateful odour;
+it painted the gorgeous plumage of the Impeyan pheasant and the
+beautiful colours and decorations of countless birds and insects and
+flowers. These, and a thousand other achievements, it has evidently
+accomplished without the help of use-inheritance. Why should it be
+thought incapable of reducing a pigeon's wing or enlarging a duck's
+leg? Why should it be credited with the help of an officious ally in
+effecting comparatively slight changes, when great and striking
+modifications are effected without any such aid?
+
+
+FOOTNOTES:
+
+[15] Weismann's _Essays on Heredity_, &c. Clarendon Press, 1889.
+
+[16] _Life and Letters_, i. p. 16. Darwin's reverence for his father
+"was boundless and most touching. He would have wished to judge
+everything else in the world dispassionately, but anything his father
+had said was received with almost implicit faith; ... he hoped none of
+his sons would ever believe anything because he said it, unless they
+were themselves convinced of its truth--a feeling in striking contrast
+with his own manner of faith" (_Life and Letters_, i. pp. 10, 11).
+
+[17] _Ibid._, i. p. 38.
+
+[18] _Life and Letters_, ii. p. 14.
+
+[19] _Origin of Species_, pp. 117, 118.
+
+[20] _Ibid._, p. 180.
+
+[21] _Contemporary Review_, December, 1875, pp. 89, 93.
+
+[22] _Variation of Animals and Plants under Domestication_, i. 292.
+
+[23] _Variation of Animals and Plants under Domestication_, i. 299-301.
+
+[24] To keep pace with this lateral increase in weight, the leg-bones
+should have lengthened considerably so that their total deficiency in
+proportional length is 17 per cent.,--a changed proportion which being
+_linear_ is more excessive than the increase of weight by 28 per cent.
+So marked is the effect of the combined thickening and shortening that
+in the Aylesbury breed--which is the most typically representative
+one--the leg-bones have become 70 per cent. heavier than they should be
+if their thickness had continued to be proportional to their length.
+
+[25] This excessive thickening under disuse appears to be due partly to
+a positive lateral enlargement or increase of proportional weight of
+about 7-1/2 per cent., and partly to a shortening of about 15 per cent.
+Carefully calculated, the reduction of the weight of the wing-bones in
+this breed is only 8·3 per cent. relatively to the whole skeleton, or
+only 5 per cent. relatively to the skeleton _minus_ legs and wings. The
+latter method is the more correct, since the excessive weight of the
+leg-bones increases the weight of the skeleton more than the diminished
+weight of the wing-bones reduces it.
+
+[26] _Variation of Animals and Plants under Domestication_, i. 284.
+
+[27] _Variation of Animals and Plants under Domestication_, i. 184, 185.
+
+[28] _Ibid._, i. 144, 145.
+
+[29] _Ibid._, i. 185.
+
+[30] _Variation of Animals and Plants under Domestication_, i. 175.
+
+[31] _Variation of Animals and Plants under Domestication_, i. 184. I
+suspect that Darwin was in poor health when he wrote this page. He nods
+at least four times in it. Twice he speaks of "twelve" breeds where he
+obviously should have said eleven.
+
+[32] If a prominent breast is admired and selected by fanciers, the
+sternum might shorten in assuming a more forward and vertical position.
+If the shortening of the sternum is entirely due to disuse, it seems
+strange that Darwin has not noticed any similar shortening in the
+sternum of the duck. But selection has not tended to make the duck
+elegant, or "pigeon-breasted"; it has enlarged the abdominal sack
+instead, besides allowing the addition of an extra rib in various cases.
+
+[33] _Variation of Animals and Plants under Domestication_, 144, 175.
+
+[34] _Variation of Animals and Plants under Domestication_, i. 179.
+
+[35] In the six largest breeds the shortening of the sternum is nearly
+twice as great as in the three smaller breeds which remain nearest the
+rock-pigeon in size. We can hardly suppose that use-inheritance
+especially affects the eight breeds that have varied most in size. If we
+exclude these, there is only a total shortening of 7 per cent. to be
+accounted for.
+
+[36] _Variation of Animals and Plants under Domestication_, i. 183, 186.
+
+[37] _Variation of Animals and Plants under Domestication_, i. 130, 135;
+ii. 288.
+
+[38] _Encyclopędia Britannica_, article "Zoology."
+
+[39] _Variation of Animals and Plants under Domestication_, ii. 367.
+
+[40] _Variation of Animals and Plants under Domestication_, ii. 367. Why
+then does the cheetah inherit ancestral habits so inadequately that it
+is useless for the chase unless it has first learned to hunt for itself
+before being captured? (ii. 133).
+
+[41] _Descent of Man_, p. 33.
+
+[42] _Origin of Species_, pp. 210, 211.
+
+[43] E. S. Delamer on _Pigeons and Rabbits_, pp. 132, 103. For other
+points referred to, see pages 133, 102, 100, 95, 131.
+
+[44] _Origin of Species_, pp. 188, 110; _Descent of Man_, pp. 32-35;
+_Variation of Animals and Plants under Domestication_, ii. 289, 293. Use
+or disuse during lifetime of course co-operates, and in some cases, as
+in that of the canoe Indians, may be the principal or even perhaps the
+_sole_ cause of the change.
+
+[45] For the importance of panmixia as invalidating Darwin's strongest
+evidence for use-inheritance--namely, that drawn from the effects of
+disuse in highly-fed domestic animals where there is supposed to be no
+economy of growth--see Professor Romanes on Panmixia, _Nature_, April 3,
+1890.
+
+[46] _Descent of Man_, p. 33.
+
+[47] _Descent of Man_, p. 33.
+
+[48] _Variation of Animals and Plants under Domestication_, i., 453.
+
+[49] _Descent of Man_, p. 33.
+
+[50] _Descent of Man_, p. 33.
+
+[51] Wallace shows that the changes in our domestic animals, if spread
+over the thousands of years since the animals were first tamed, must be
+extremely insignificant in each generation, and he concludes that such
+infinitesimal effects of use and disuse would be swallowed up by the far
+greater effects of variation and selection (_Darwinism_, p. 436).
+Professor Romanes has replied to him in the _Contemporary Review_
+(August 1889), showing that this is no disproof of the existence of the
+minor factor, inasmuch as slight changes in each generation need not
+necessarily be matters of life and death to the individual, although
+their cumulative development by use-inheritance might eventually become
+of much service. But selection would favour spontaneous variations of a
+similarly serviceable character. The slightest tendency to eliminate the
+extreme variations in either direction would proportionally modify the
+average in a breed. Use-inheritance appears to be so relatively weak a
+factor that probably neither proof nor disproof of its existence can
+ever be given, owing to the practical impossibility of disentangling its
+effects (if any) from the effects of admittedly far more powerful
+factors which often act in unsuspected ways. Thus wild ducklings, which
+can easily be reared by themselves, invariably "die off" if reared with
+tame ones (_Variation_, &c., i. 292, ii. 219). They cannot get their
+fair share in the competition for food, and are completely eliminated.
+Professor Romanes fully acknowledges that there is the "gravest possible
+doubt" as to the transmission of the effects of disuse (Letter on
+Panmixia, _Nature_, March 13, 1890).
+
+[52] _Variation of Animals and Plants under Domestication_, ii. 287-289.
+
+[53] _Descent of Man_, pp. 612, 131.
+
+
+
+
+INHERITED INJURIES.
+
+
+INHERITED MUTILATIONS.
+
+The almost universal _non-inheritance_ of mutilations seems to me a far
+more valid argument _against_ a general law of modification-inheritance
+than the few doubtful or abnormal cases of such inheritance can furnish
+in its favour. No inherited effect has been produced by the docking of
+horses' tails for many generations, or by a well-known mutilation which
+has been practised by the Hebrew race from time immemorial. As lost or
+mutilated parts are reproduced in offspring independently of the
+existence of those parts in the parent, there is the less reason to
+suppose that the particular condition of parental parts transmits
+itself, or tends to transmit itself, to the offspring. So unsatisfactory
+is the argument derivable from inherited mutilations that Mr. Spencer
+does not mention them at all, and Darwin has to attribute them to a
+special cause which is independent of any general theory of
+use-inheritance.[54]
+
+Darwin's most striking case--and to my mind the only case of any
+importance--is that of Brown-Séquard's epileptic guinea-pigs, which
+inherited the mutilated condition of parents who had gnawed off their
+own gangrenous toes when anęsthetic through the sciatic nerve having
+been divided.[55] Darwin also mentions a cow that lost a horn by
+accident, followed by suppuration, and subsequently produced three
+calves which had on the same side of the head, instead of a horn, a bony
+lump attached merely to the skin. Such cases may seem to prove that
+mutilation _associated with morbid action_ is occasionally inherited or
+repeated with a promptitude and thoroughness that contrast most
+strikingly with the imperceptible nature of the immediate inheritance of
+the effects of use and disuse; but they by no means prove that
+mutilation in general is inheritable, and they are absolutely no proof
+whatever of a _normal_ and non-pathological tendency to the inheritance
+of acquired characters. Those who accept Darwin's special explanation
+of the supposed inheritance of mutilations, ought to notice that his
+explanation applies equally well under a theory which is strongly
+adverse to use-inheritance--namely, Galton's idea of the sterilization
+and complete "using up" of otherwise reproductive matter in the growth
+and maintenance of the personal structure.
+
+Darwin's explanation of inherited mutilations--which, as he notes, occur
+"especially or perhaps exclusively" when the injury has been followed by
+disease[56]--is that all the representative gemmules which would develop
+or repair or reproduce the injured part are attracted to the diseased
+surface during the reparative process and are there destroyed by the
+morbid action.[57] Hence they cannot reproduce the part in offspring.
+This explanation by no means implies that mutilation would _usually_
+affect the offspring. On the contrary, in all ordinary cases of
+mutilation the purely atavistic elements or gemmules would be set free
+from any modifying influence of the non-existent or mutilated part. The
+gemmules--as in Galton's theory of heredity and with neuter
+insects--might be perfectly independent of pangenesis and the normal
+inheritance of acquired characters. Such self-multiplying gemmules
+without pangenesis would enable us to understand both the excessive
+weakness or non-existence of normal use-inheritance, and the excessive
+strength and abruptness of the effect of their partial destruction under
+special pathological conditions.
+
+The series of epileptic phenomena that can be excited by tickling a
+certain part of the cheek and neck of the adult guinea-pig during the
+growth and rejoining of the ends of the severed nerve, are said to be
+repeated with striking accuracy of detail in the young who inherit
+mutilated toes; but as epilepsy is often due to some _one_ exciting
+cause or morbid condition, the single transmission of a highly morbid
+condition of the system might easily reproduce the whole chain of
+consequences and might also have caused the loss of toes.
+
+The particulars of the guinea-pig cases are very inadequately
+recorded,[58] but the results are so anomalous[59] that Brown-Séquard's
+own conclusion is that the epilepsy and the inherited injuries are
+_not_ directly transmitted, but that "what is transmitted is the morbid
+state of the nervous system." He thinks that the missing toes may
+"possibly" be exceptions to this conclusion, "but the other facts only
+imply the transmission of a morbid state of the sympathetic or sciatic
+nerve or of a part of the medulla oblongata." Until we can tell what is
+transmitted, we are not in a position to determine whether there is any
+true inheritance or only an exaggerated simulation of it under peculiar
+circumstances. When the actual observers believe that the mutilations
+and epilepsy are not the cause of their own repetition, and when these
+observers guard themselves by such phrases as, "if any conclusion can at
+present be drawn from those facts," we who have only incomplete reports
+to guide us may well be excused if we preserve an even more pronounced
+attitude of caution and reserve.[60] The morbid state of the system may
+be wholly due to general injury of the germs rather than to specific
+inheritance.
+
+Weismann suggests that the morbid condition of the nervous system may be
+due to some infection such as might arise from microbes, which find a
+home in the mutilated and disordered nervous system in the parent, and
+subsequently transmit themselves to the offspring through the
+reproductive elements, as the infections of various diseases appear to
+do--the muscardine silkworm disease in particular being known to be
+conveyed to offspring in this manner.
+
+But whether we can discover the true explanation or not, inherited
+mutilations can hardly be accounted for as the result of a general
+tendency to inherit acquired modifications. How could a factor which
+seems to be totally inoperative in cases of ordinary mutilation, and
+only infinitesimally operative in transmitting the normal effects of use
+and disuse, suddenly become so powerful as to completely overthrow
+atavism, and its own tendency to transmit the non-mutilated type of one
+of the parents and of the non-mutilated type presented by the injured
+parent in earlier life? Does not so striking and abrupt an
+intensification of its usually insignificant power demand an explanation
+widely different from that which might account for the extremely slow
+and slight inheritance of the normal effects of use and disuse? Surely
+it would be better to suspend one's judgment as to the true explanation
+of highly exceptional and purely pathological cases rather than resort
+to an hypothesis that creates more difficulties than it solves.
+
+
+THE MOTMOT'S TAIL.
+
+The narrowing of the long central tail feathers of the motmot is
+attributed to the inherited effects of habitual mutilation (_Descent of
+Man_, pp. 384, 603). But in the specimens at South Kensington[61] the
+narrowness extends upwards much beyond the habitually denuded part, and
+the broadened end is the broadest part of the whole feather. If the
+inherited effect of an inch or two of denudation extends from three to
+six inches upwards, why has it not also extended two inches downwards so
+as to narrow the broadened end? The narrowness seems to be a mainly
+relative or negative effect produced by the broadening out of a long
+tapering feather at its end under the influence of sexual selection.
+Several other birds have similarly narrowed or spoon-shaped feathers and
+do not bite them. Is it not more feasible to suppose that this
+attractive peculiarity first suggested its artificial intensification,
+than to suppose that the bird began nibbling without any definite cause?
+Sexual selection would then encourage the habit. Anyhow, it is as
+impossible to show that the mutilation preceded the narrowing as it is
+to show that tonsure preceded baldness.
+
+
+OTHER INHERITED INJURIES MENTIONED BY DARWIN.
+
+Darwin quotes some cases from Dr. Prosper Lucas's "long" but weak and
+unsatisfactory "list of inherited injuries."[62] But Lucas was somewhat
+credulous. One of his cases is that many girls were born in London
+without mammę through the injurious effect of certain corsets on the
+mothers. He also gives a long account of a Jew who could read through
+the thick covers of a book, and whose son inherited this "hyperęsthesia"
+of the sense of sight in a still more remarkable degree (i. 113-119).
+Evidently Lucas's cases cannot be accepted without some amount of
+reserve.
+
+The cases of the three calves which inherited the one-horned condition
+of the cow, the two sons who inherited a father's crooked finger, and
+the two sons who were microphthalmic on the same side as their father
+had lost an eye, may be due to mere coincidence; or an inherited
+constitutional tendency or liability might lead to somewhat similar
+results in parent and offspring[63]--just as the tendency to certain
+fatal diseases or to suicide may produce similar results in father and
+son, although the artificially-produced hanging or apoplexy obviously
+cannot be directly transmitted. That more than one of the offspring was
+affected does not render the chances against coincidence "almost
+infinitely great," as Darwin mistakenly supposes. It "frequently occurs"
+that a man's sons or daughters may _all_ exhibit either a latent or a
+newly-developed congenital peculiarity previously unknown;[64] and the
+coincidence may merely be that one of the parents accidentally suffered
+a similar kind of injury--a kind of coincidence which must of course
+occasionally occur, and which may have been partly caused by a latent
+tendency. The chances against coincidence are indeed great, but the
+cases appear to be correspondingly rare.
+
+Darwin acknowledges that many supposed instances of inherited mutilation
+may be due to coincidence; and there is apparently no more reason for
+attributing inherited scars, &c., to any special form of heredity than
+to the effect of the mother's imagination on the unborn babe--a popular
+but fallacious belief in corroboration of which far more alleged
+instances could be collected than of the inheritance of injuries.
+
+As an instance of the coincidences that occur, I may mention that a
+friend of mine has a daughter who was born with a small hole in one ear,
+just as if it were already pierced for the earring which she has since
+worn in it. I suppose, however, that no one will venture to claim this
+as an instance of the inheritance of a mutilation practised by female
+ancestors, especially as such holes are not altogether unknown or
+inexplicable, though very rarely occurring low down in the lobe of the
+ear.[65]
+
+Many cases are known of the inheritance of mutilations or malformations
+arising congenitally from some abrupt variation in the reproductive
+elements. In such cases as the one-eared rabbits, the two-legged pigs,
+the three-legged dogs, the one-horned stags, hornless bulls, earless
+rabbits, lop-eared rabbits, tailless dogs, &c., if the father or the
+mother or the embryo had suffered from some accident or disease which
+might plausibly have been assigned as the cause of the original
+malformation, these transmitted defects would readily be cited as
+instances of the inheritance of an accidentally-produced modification.
+
+The inheritance of exostoses on horses' legs may be the inheritance of a
+constitutional tendency rather than of the effect of the parents' hard
+travelling. Horses congenitally liable to such formations would transmit
+the liability,[66] and this might readily be mistaken for inheritance of
+the results of the liability. An apparent increase in this liability
+might arise from greater attention being now paid to it, or from
+increased use of harder roads; or a real increase might be due to
+panmixia and some obscure forms of correlation.
+
+
+QUASI-INHERITANCE.
+
+Of course artificially-caused ill-health or weakness in parents will
+tend in a general way to injure the offspring. But deterioration thus
+caused is only a form of quasi-inheritance, as I should prefer to call
+it. Semi-starvation in a new-born babe is _not_ truly inherited from its
+half-starved mother, but is the direct result of insufficient
+nourishment. The general welfare of germs--as of parasites--is
+necessarily bound up with that of the organism which feeds and shelters
+them, but this is not heredity, and is quite irrelevant to the question
+whether particular modifications are transmitted or not.
+
+Another form of quasi-inheritance is seen in the communication of
+certain infections to offspring. Not being transmitted by the action of
+the organism so much as in defiance of it, such diseases are not truly
+hereditary, though for convenience' sake they are usually so described.
+
+A perversion or prevention of true inheritance is also seen in the
+action of alcohol, or excessive overwork, or any other cause which by
+originating morbid conditions in individuals may also injure the
+reproductive elements.
+
+These forms of quasi-inheritance are, of course, highly important so far
+as the improvement of the race is concerned. So, too, is the fact that
+improved or deteriorated habits and thoughts are transmitted by personal
+teaching and influence and are cumulative in their effect. But all this
+must not be confounded with the inheritance of acquired characters.
+Cases of quasi-inheritance may perhaps be most readily distinguished
+from cases of true inheritance by the time test. When a modification
+acquired in adult life is promptly communicated to the child in early
+life or from birth, it may rightly be suspected that the inheritance,
+like that of money or title, is not truly congenital, but is extraneous
+or even anti-congenital in its nature. Judged by such a standard, the
+inherited injuries in Brown-Séquard's guinea-pigs are only exceptional
+cases of quasi-inheritance, and are not necessarily indicative of any
+general rule affecting true inheritance.
+
+
+FOOTNOTES:
+
+[54] A very able anatomist of my acquaintance denies the inheritance of
+mutilations and injuries, although he strongly believes in the
+inheritance of the effects of use and disuse.
+
+[55] _Variation of Animals and Plants under Domestication_, i. 467-469.
+Lost toes were only seen by Dr. Dupuy in three young out of two hundred.
+Obersteiner found that most of the offspring of his epileptic
+guinea-pigs were injuriously affected, being weakly, small, paralysed in
+one or more limbs, and so forth. Only two were epileptic, and both were
+weakly and died early (Weismann's _Essays_, p. 311). A morbid condition
+of the spinal cord might affect the hind limbs especially (as in
+paraplegia) and might occasionally cause loss of toes in the embryo by
+preventing development or by ulceration. Brown-Séquard does not say that
+the defective feet were on the same side as in the parents (_Lancet_,
+Jan., 1875, pp. 7, 8).
+
+[56] _Variation of Animals and Plants under Domestication_, ii. 57.
+
+[57] _Ibid._, ii. 392. Perhaps it might be better to suppose that the
+_best_ gemmules were sacrificed in repairing the injured _nerve_, and
+hence only inferior substitutes were left to take their place, and could
+only imperfectly reproduce the injured part of the nervous system in
+offspring.
+
+[58] Hence perhaps Mr. Spencer's error in representing the epileptic
+liability as permanent and as coming on _after_ healing (_Factors of
+Organic Evolution_, p. 27).
+
+[59] It is not claimed that the imperfect foot was on the same side of
+the body as in the parent, and where parents had lost _all_ the toes of
+a foot, or the whole foot, the few offspring affected usually had lost
+only two toes out of the three, or only a part of one or two or three
+toes. Sometimes the offspring had toes missing on _both_ hind feet,
+although the parent was only affected in _one_. _One_ diseased ear and
+eye in the parent was "generally" or "always" succeeded by _two_ equally
+affected ears and eyes in the offspring (cf. _Pop. Science Monthly_, New
+York, xi. 334). The important law of inheritance at corresponding
+periods was also set aside. Gangrene or inflammation commenced in both
+ears and both eyes soon after birth (pointing possibly to infection of
+some kind); the epileptic period commenced "perhaps two months or more
+after birth," while the loss of toes had occurred before birth. In no
+case, as Weismann points out, is the original mutilation of the nervous
+system ever transmitted. Even where an extirpated ganglion was never
+regenerated in the parent, the offspring always regained the part in an
+apparently perfect condition. On the whole the conflicting results ought
+to be as puzzling to those who may attribute them to a universal
+tendency to inherit the exact condition of parents as they are to those
+who, like myself, are sceptical as to the existence of such a law or
+tendency.
+
+[60] The various results need to be fully and impartially recorded, and
+they should also be well tested and confirmed in proportion as they
+appear improbable and contrary to general experience. Professor Romanes
+has been carrying out the necessary experiments for some time past.
+
+[61] Natural History Museum, central hall, third recess on the left.
+
+[62] _Traité de l'Hérédité_, ii. 489; _Variation of Animals and Plants
+under Domestication_, i. 469. If injuries are inherited, why has the
+repeated rupture of the hymen produced no inherited effect?
+
+[63] Compare the three cases of crooked fingers given in _Variation of
+Animals and Plants under Domestication_, ii. 55, 240.
+
+[64] _Ibid._, i. 460. Thus, where two brothers married two sisters all
+the seven children were perfect albinos, although none of the parents or
+their relatives were albinos. In another case the nine children of two
+sound parents were all born blind (ii. 322).
+
+[65] See pp. 179-182, _Evolution and Disease_, by J. Bland Sutton, to
+whom and to our mutual friend Dr. D. Thurston I am indebted for
+information on various points.
+
+[66] _Variation of Animals and Plants under Domestication_, ii. 290; i.
+454.
+
+
+
+
+MISCELLANEOUS CONSIDERATIONS.
+
+
+TRUE RELATION OF PARENTS AND OFFSPRING.
+
+It is difficult to entirely free ourselves from the flattering and
+almost universal idea that parents are true originators or creators of
+copies of themselves. But the main truth, if not the whole truth, is
+that they are merely the transmitters of types of which they and their
+offspring are alike more or less similarly moulded resultants. A parent
+is a trustee. He transmits, not himself and his own modifications, but
+the stock, the type, the representative elements, of which he is a
+product and a custodian in one. It seems probable that he has no more
+definite or "particulate" influence over the reproductive elements
+within him than a mother over the embryo or a vessel over its cargo.
+Parent and offspring are like successive copies of books printed from
+the same "type." A battered letter in the "type" will display its
+effects in both earlier and later copies alike, but a purely extraneous
+or acquired flaw in the first copy is not necessarily repeated in
+subsequent copies. Unlike printer's type, however, the material source
+of heredity is of a fluctuating nature, consisting of competing elements
+derived from two parents and from innumerable ancestors.
+
+Galton compares parent and child to successive pendants on the same
+chain. Weismann likens them to successive offshoots thrown up by a long
+underground root or sucker. Such comparisons indicate the improbability
+of acquired modifications being transmitted to offspring.
+
+That parts are developed in offspring independently of those parts in
+parents is clear. Mutilated parents transmit parts which they do not
+possess. The offspring of young parents cannot inherit the later stages
+of life from parents who have not passed through them. Cases of remote
+reversion or atavism show that ancestral peculiarities can transmit
+themselves in a latent or undeveloped condition for hundreds or
+thousands of generations. Many obvious facts compelled Darwin to suppose
+that vast numbers of the reproductive gemmules in an individual are not
+thrown off by his own cells, but are the self-multiplying progeny of
+ancestral gemmules. Galton restricts the production of gemmules by the
+personal structure to a few exceptional cases, and would evidently like
+to dispense with pangenesis altogether, if he could only be sure that
+acquired characters are never inherited. Weismann entirely rejects
+pangenesis and the inheritance of acquired characters. This enables him
+to explain heredity by his theory of the "Continuity of the
+Germ-plasm."[67] Parent and offspring are alike successive products or
+offshoots of this persistent germ-substance, which obviously would not
+be correspondingly affected by modifications of parts in parents, and so
+would render the transmission of acquired characters impossible.
+
+
+INVERSE INHERITANCE.
+
+Mr. Galton contends that the reproductive elements become sterile when
+used in forming and maintaining the individual, and that only a small
+proportion of them are so used.[68] He holds that the next generation
+will be formed entirely, or almost entirely, from the residue of
+undeveloped germs, which, not having been employed in the structure and
+work of the individual, have been free to multiply and form the
+reproductive elements whence future individuals are derived. Hence the
+singular inferiority not infrequently displayed by the children of men
+of extraordinary genius, especially where the ancestry has been only of
+a mediocre ability. The valuable germs have been used up in the
+individual, and rendered sterile in the structure of his person. Hence,
+too, the "strong tendency to deterioration in the transmission of every
+exceptionally gifted race." Mr. Galton's hypothesis "explains the fact
+of certain diseases skipping one or more generations," and it "agrees
+singularly well with many classes of fact;" and it is strongly opposed
+to the theory of use-inheritance. The elements which are used die almost
+universally without germ progeny: the germs which are _not_ used are the
+great source of posterity. Hence, when the germs or gemmules which
+achieve development are either better or worse than the residue, the
+qualities transmitted to offspring will be of an inverse character. If
+brain-work attracts, develops _and sterilizes_ the best gemmules, the
+ultimate effect of education on the intellect of posterity may differ
+from its immediate effect.
+
+
+EARLY ORIGIN OF THE OVA.
+
+As the ova are formed at as early a period as the rest of the maternal
+structure, Galton notices that it seems improbable that they would be
+correspondingly affected by subsequent modifications of parental
+structure. Of course it is not certain that this is a valid argument. We
+know that the paternal half of the reproductive elements does not enter
+the ovum till a comparatively late stage in its history, and it is quite
+possible that maternal elements or gemmules may also enter the ovum from
+without. If reproductive elements were confined to one special part or
+organ, we should be unable to explain the reproduction of lost limbs in
+salamanders, and the persistent effect of intercrossing on subsequent
+issue by the same mother, and the propagation of plants from shoots, or
+of the begonia from minute fragments of leaves, or the development of
+small pieces of water-worms into complete animals.
+
+
+MARKED EFFECTS OF USE AND DISUSE ON THE INDIVIDUAL.
+
+These are, to some extent, an argument against the cumulative
+inheritance of such effects. When a nerve atrophies from disuse, or a
+duct shrivels, or bone is absorbed, or a muscle becomes small or flabby,
+it proves, so far, that the average effect of use through enormous ages
+is _not_ transmitted. When the fibula of a dog's leg thickens by 400 per
+cent. to a size "equal to or greater than" that of the removed tibia
+which previously did the work,[69] it shows that in spite of disuse for
+countless generations, the "almost filiform" bone has retained a
+potentiality of development which is fully equal to that possessed by
+the larger one which has been constantly used. When, after being reared
+on the ailanthus, the caterpillars of the _Bombyx hesperus_ die of
+hunger rather than return to their natural food, the inherited effect of
+ancestral habit does not seem to be particularly strong. Neither is
+there any strongly-inherited effect of long-continued ancestral wildness
+in many animals which are easily tamed.
+
+
+WOULD NATURAL SELECTION FAVOUR USE-INHERITANCE?
+
+If use-inheritance is really one of the factors of evolution, it is
+certainly a subordinate one, and an utterly helpless one, whenever it
+comes into conflict with the great ruling principle of Selection. Would
+this dominant cause of evolution have favoured a tendency to
+use-inheritance if such had appeared, or would it have discouraged and
+destroyed it? We have already seen that use-inheritance is unnecessary,
+since natural selection will be far more effective in bringing about
+advantageous modifications; and if it can be shown that use-inheritance
+would often be an evil, it then becomes probable that on the whole
+natural selection would more strongly discourage and eliminate it as a
+hostile factor than it might occasionally favour such a tendency as a
+totally unnecessary aid.
+
+
+USE-INHERITANCE AN EVIL.
+
+Use-inheritance would crudely and indiscriminately proportion parts to
+actual work done--or rather to the varying _nourishment and growth_
+resulting from a multiplicity of causes--and this in its various details
+would often conflict most seriously with the real necessities of the
+case, such as occasional passive strength, or appropriate shape,
+lightness and general adaptation. If its accumulated effects were not
+corrected by natural or sexual selection, horns and antlers would
+disappear in favour of enlarged hoofs. The elephant's tusks would become
+smaller than its teeth. Men would have callosities for sitting on, like
+certain monkeys, and huge corns or hoofs for walking on. Bones would
+often be modified disastrously. Thus the condyle of the human jaw would
+become larger than the body of the jaw, because as the fulcrum of the
+lever it receives more pressure. Some organs (like the heart, which is
+always at work) would become inconveniently or unnecessarily large.
+Other absolutely indispensable organs, which are comparatively passive
+or are very seldom used, would dwindle until their weakness caused the
+ruin of the individual or the extinction of the species. In eliminating
+various evil results of use-inheritance, natural selection would be
+eliminating use-inheritance itself. The displacement of Lamarck's theory
+by Darwin's shows that the effects of use-inheritance often differ from
+those required by natural selection; and it is clear that the latter
+factor must at least have reduced use-inheritance to the very minor
+position of comparative feebleness and harmlessness assigned to it by
+Darwin.
+
+Use-inheritance would be ruinous through causing unequal variation in
+co-operative parts--of which Mr. Spencer may accept his own instances of
+the jaws and teeth, and the cave-crab's lost eyes and persistent
+eye-stalks, as typical examples. That the variation would be unequal
+seems almost self-evident from the varying rapidity and extent of the
+effects of use and disuse on different tissues and on different parts of
+the general structure. The optic nerve may atrophy in a few months from
+disuse consequent on the loss of the eye. Some of the bones of the
+rudimentary hind legs of the whale are still in existence after disuse
+for an enormous period. Evidently use-inheritance could not equally
+modify the turtle and its shell, or the brain and its skull; and in
+minor matters there would be the same incongruity of effect. Thus, if
+the molar teeth lengthened from extra use the incisors could not meet.
+Unequal and indiscriminate variation would throw the machinery of the
+organism out of gear in innumerable ways.
+
+Use-inheritance would perpetuate various evils. We are taught, for
+instance, that it perpetuates short-sight, inferior senses, epilepsy,
+insanity, nervous disorders, and so forth. It would apparently transmit
+the evil effects of over-exertion, disuse, hardship, exposure, disease
+and accident, as well as the defects of age or immaturity.
+
+Would it not be better on the whole if each individual took a fresh
+start as far as possible on the advantageous typical lines laid down by
+natural selection? Through the long stages of evolution from primęval
+protoplasm upwards, such species as were least affected by
+use-inheritance would be most free to develop necessary but seldom-used
+organs, protective coverings such as shells or skulls, and natural
+weapons, defences, ornaments, special adaptations, and so forth; and
+this would be an advantage--for survival would obviously depend on the
+_importance_ of a structure or faculty in deciding the struggle for
+existence and reproduction, and not on the total amount of its using or
+nourishment. If natural selection had on the whole favoured this
+officious ally and frequent enemy, surely we should find better evidence
+of its existence.
+
+Without laying undue stress upon the evil effects of use-inheritance, a
+careful examination of them in detail may at least serve to
+counter-balance the optimistic _a priori_ arguments for belief in that
+plausible but unproven factor of evolution.
+
+The benefits derivable from use-inheritance are largely illusory. The
+effects of _use_, indeed, are generally beneficial up to a certain
+point; for natural selection has sanctioned or evolved organs which
+possess the property or potentiality of developing to the right extent
+under the stimulus of use or nourishment. But use-_inheritance_ would
+cumulatively alter this individual adaptability, and would tend to fix
+the size of organs by the average amount of ancestral use or disuse
+rather than by the actual requirements of the individual. Of course
+under changed conditions involving increased or lessened use of parts it
+might become advantageous; but even here it may prove a decided
+hindrance to adaptive evolution in some respects as well as an
+unnecessary aid in others. Thus in the case of animals becoming heavier,
+or walking more, it would _lengthen_ the legs although natural selection
+might require them to be shortened. In the Aylesbury duck and the Call
+duck, if use-inheritance has increased the dimensions of the bones and
+tendons of the leg, natural selection has had to counteract this
+increase so far as length is concerned, and to effect 8 per cent. of
+shortening besides. If use-inheritance thickens bones without
+proportionally lengthening them, it would hinder rather than help the
+evolution of such structures as the long light wings of birds, or the
+long legs and neck of the giraffe or crane.
+
+
+VARIED EFFECTS OF USE AND DISUSE.
+
+The changes which we somewhat roughly and empirically group together as
+the effects of "use and disuse" are of widely diverse character. Thus
+bone, as the physiological fact, thickens under _alternations_ of
+pressure (and the consequent increased flow of nourishment), but
+atrophies under a steadily continued pressure; so that if the use of a
+bone involved continuous pressure, the effect of such use would be a
+partial or total absorption of that bone. Darwin shows that bone
+lengthens as well as thickens from carrying a greater weight, while
+tension (as seen in sailors' arms, which are used in pulling) appears to
+have an equally marked effect in shortening bones (_Descent of Man_, p.
+32). Thus different kinds of use may produce opposite results. The
+cumulative inheritance of such effects would often be mischievous. The
+limbs of the sloth and the prehensile tail of the spider monkey would
+continually grow shorter, while the legs of the evolving elephant or
+rhinoceros might lengthen to an undesirable extent. Such cumulative
+tendencies of use-inheritance, if they exist, are obviously well kept
+under by natural selection.
+
+Although the ultimate effect of use is generally growth or enlargement
+through increased flow of blood, the first effect usually is a loss of
+substance, and a consequent diminution of size and strength. When the
+loss exceeds the growth, use will diminish or deteriorate the part used,
+while disuse would enlarge or perfect it. Teeth, claws, nails, skin,
+hair, hoofs, feathers, &c., may thus be worn away faster than they can
+renew themselves. But this wearing away usually stimulates the repairing
+process, and so increases the rate of growth; that is, it will increase
+the size produced, if not the size retained. Which effect of use does
+use-inheritance transmit in such cases--the increased rate of growth, or
+the dilapidation of the worn-out parts? We can hardly suppose that both
+these effects of use will be inherited. Would shaving destroy the beard
+in time or strengthen it? Will the continued shearing of sheep increase
+or lessen the growth of wool? What will be the ultimate effect of
+plucking geese's quills, and of the eider duck's abstraction of the down
+from her breast? If the mutilated parts grow stronger or more
+abundantly, why were the motmot's feathers alleged to be narrowed by the
+inherited effects of ancestral nibbling?
+
+The "use" or "work" or "function" of muscles, nerves, bones, teeth,
+skin, tendon, glands, ducts, eyes, blood corpuscles, cilia, and the
+other constituents of the organism, is as widely different as the
+various parts are from each other, and the effects of their use or
+disuse are equally varied and complicated.
+
+
+USE-INHERITANCE IMPLIES PANGENESIS.
+
+How could the transmission of these varied effects to offspring be
+accounted for? Is it possible to believe, with Mr. Spencer, that the
+effects of use and disuse on the parts of the personal structure are
+simultaneously registered in corresponding impressions on the seminal
+germs? Must we not feel, with Darwin apparently,[70] that the _only_
+intelligible explanation of use-inheritance is the hypothesis of
+Pangenesis, according to which each modified cell, or physiological
+unit, throws off similarly-modified gemmules or parts of itself, which
+ultimately reproduce the change in offspring? If we reject pangenesis,
+it becomes difficult to see how use-inheritance can be possible.
+
+
+PANGENESIS IMPROBABLE.
+
+The more important and best-known phenomena of heredity do not require
+any such hypothesis, and leading facts (such as atavism, transmission of
+lost parts, and the general non-transmission of acquired characters) are
+so adverse to it that Darwin has to concede that many of the
+reproductive gemmules are atavistic, and that by continuous
+self-multiplication they may preserve a practical "continuity of
+germ-substance," as Weismann would term it. The idea that the
+relationship of offspring to parent is one of direct descent is, as
+Galton tells us, "wholly untenable"; and the only reason he admits some
+supplementary traces of pangenesis into his "Theory of Heredity,"[71] is
+that he may thus account for the more or less questionable cases of the
+transmission of acquired characters. But there appears to be no
+necessity even for this concession. We ought therefore to dispense with
+the useless and gratuitous hypothesis that cells multiply by throwing
+off minute self-multiplying gemmules, as well as by the well-known
+method of self-division. If pangenesis occurs, the transmission of
+acquired characters ought to be a prominent fact. The size, strength,
+health and other good or evil qualities of the cells could hardly fail
+to exercise a marked and corresponding effect upon the size and quality
+of the reproductive gemmules thrown off by those cells. The direct
+evidence tends to show that these free gemmules do not exist.
+Transfusion of blood has failed to affect inheritance in the slightest
+degree. Pangenesis, with its attraction of gemmules from all parts of
+the body into the germ-cells, and the free circulation of gemmules in
+the offspring till they hit upon or are attracted by the particular cell
+or cells, with which alone they can readily unite, seems a less feasible
+theory and less in conformity with the whole of the facts than an
+hypothesis of germ-continuity which supposes that the development of the
+germ-plasm and of the successive self-dividing cells of the body
+proceeds from within. Darwin's keen analogy of the fertilization of
+plants by pollen renders development from without conceivable, but as
+there are no insects to convey gemmules to their destination, each kind
+of gemmule would have to be exceedingly numerous and easily attracted
+from amongst an inconceivable number of other gemmules. Arguments
+against pangenesis can also be drawn from the case of neuter insects--a
+fact which seems to have escaped Darwin's notice, although he had seen
+how strongly that case was opposed to the doctrine which is the
+essential basis of the theory of pangenesis.
+
+
+SPENCER'S EXPLANATION OF USE-INHERITANCE.
+
+Mr. Spencer's explanation of the inheritance of the effects of use and
+disuse (p. 36) is that "while generating a modified _consensus_ of
+functions and of structures, the activities are at the same time
+impressing this modified _consensus_ on the sperm-cells and germ-cells
+whence future individuals are to be produced"--a proposition which reads
+more like metaphysics than science. Difficult to understand or believe
+in ordinary instances, such _consensus_-inheritance seems impossible in
+cases like that of the hive-bee. Can we suppose that the _consensus_ of
+the activities of the working bee impresses itself on the sperm-cells
+of the drones and on the germ-cells of the carefully secluded queen?
+Büchner thinks so, for he says: "Although the queens and drones do not
+now work, yet the capacities inherited from earlier times still remain
+to them, especially to the former, and are kept alive and fresh by the
+impressions constantly made upon them during life, and they are thus in
+a position to transmit them to posterity." Surely it is better to
+abandon a cherished theory than to be compelled to defend it by
+explanations which are as inconsistent as they are inadequate. New
+capacities are developed as well as old ones kept fresh. The massacre or
+expulsion of the drones would have to impress itself on the germ-cells
+of an onlooking queen, and the imprisonment of the queen on the
+sperm-cells of the drones--and in such a way, moreover, as to be
+afterwards developed into action in the neuters only. And
+use-inheritance all the while is being thoroughly overpowered by
+impression-inheritance--by the full transmission of that which is merely
+seen in others! If such a law prevails, one may feel cold because an
+ancestor thought of the frosty Caucasus. None of this absurdity would
+arise if it were clearly seen that a parent is only a trustee--that
+transmission and development are perfectly distinct--that parental
+modifications are irrelevant to those transmitted to offspring.
+
+
+FOOTNOTES:
+
+[67] _Essays on Heredity_, p. 104. Weismann's theory is clear, simple
+and convenient, but incomplete; for, unlike Darwin's theory of
+pangenesis, it scarcely attempts any real explanation of the extremely
+complex potentialities possessed by the reproductive elements. Perhaps
+we might retain Darwin's self-multiplying gemmules without supposing
+them to be thrown off by the cells, which will no longer be credited
+with _two_ modes of multiplication. These minute germs or gemmules may
+have been evolved by natural selection playing upon the sample germs
+that achieve development; and they may exist either separately, or
+(preferably but perhaps not invariably) in aggregates to form Weismann's
+germ-plasm.
+
+[68] _Contemporary Review_, Dec., 1875, p. 88.
+
+[69] _Variation of Animals and Plants under Domestication_, ii. 286.
+
+[70] _Variation of Animals and Plants under Domestication_, ii. 388,
+398, 367; _Life and Letters_, iii. 44.
+
+[71] _Contemporary Review_, Dec., 1875, pp. 94, 95.
+
+
+
+
+CONCLUSIONS.
+
+
+USE-INHERITANCE DISCREDITED AS UNNECESSARY, UNPROVEN, AND IMPROBABLE.
+
+General experience teaches that acquired characters are not usually
+inherited; and investigation shows that the apparent exceptions to this
+great rule are probably fallacious. Even the alleged instances of
+use-inheritance culled by such great and judicious selectors as Darwin
+and Spencer break down upon examination; for they can be better
+explained without use-inheritance than with it. On the other hand, the
+adverse facts and considerations are almost strong enough to prove the
+actual non-existence of such a law or tendency. There is no need to
+undertake the apparently impossible task of demonstrating an absolute
+negative. It will be enough to ask that the Lamarckian factor of
+use-inheritance shall be removed from the category of accredited factors
+of evolution to that of unnecessary and improbable hypotheses. The main
+explanation or source of the fallacy may be found in the fact that
+natural selection frequently imitates some of the more obvious effects
+of use and disuse.
+
+
+MODERN RELIANCE ON USE-INHERITANCE MISPLACED.
+
+Modern philanthropy--so far at least as it ever studies ultimate
+results--constantly relies on this ill-founded belief as its
+justification for ignoring the warnings of those who point out the
+ultimately disastrous results of a systematic defiance or reversal of
+the great law of natural selection. This reliance finds strong support
+in Mr. Spencer's latest teachings, for he holds that the inheritance of
+the effects of use and disuse takes place universally, and that it is
+now "the chief factor" in the evolution of civilized man (pp. 35, 74,
+iv)--natural selection being quite inadequate for the work of
+progressive modification. Practically he abandons the hope of evolution
+by natural selection, and substitutes the ideal of a nation being
+"modified _en masse_ by transmission of the effects" of its institutions
+and habits. Use-inheritance will "mould its members far more rapidly and
+comprehensively" than can be effected by the survival of the fittest
+alone.
+
+But could we rely upon the aid of use-inheritance if it really were a
+universal law and not a mere simulation of one? Let us consider some of
+the features of this alleged factor of evolution, seeing that it is
+henceforth to be our principal means of securing the improvement of our
+species and our continued adaptation to the changing conditions of a
+progressive civilization.
+
+It is curiously uncertain and irregular in its action. It diminishes or
+abolishes some structures (such as jaws or eyes) without correspondingly
+diminishing or abolishing other equally disused and closely related
+parts (such as teeth, or eye-stalks). It thickens ducks' leg-bones while
+allowing them to shorten. It shortens the disused wing-bones of ducks
+and the leg-bones of rabbits while allowing them to thicken; and yet in
+other cases it greatly reduces the thickness of bones without shortening
+them. It transmits tameness most powerfully in an animal which usually
+cannot acquire it. It aids in webbing the feet of water-dogs, but fails
+to web the feet of the water-hen or to remove the web in the feet of
+upland geese.[72] It allows the disused fibula to retain a potentiality
+of development fully equal to that possessed by the long-used tibia. It
+lengthens legs because they are used in supporting the body, and
+shortens arms because they are used in pulling. Whether it enlarges
+brain if used in one way and diminishes it if used in another, we cannot
+tell; but it must obviously deaden nervous sensibilities in some cases
+and intensify them in others. It enlarges hands long before they are
+used, and thickens soles long before the time for walking on them. At
+the same time, as if by an oversight, it so delays its transmission of
+the habit of walking on these thickened soles, that the gradual and
+tedious acquisition of the non-transmitted habit costs the infant much
+time and trouble and often some pain and danger. Yet where aided by
+natural selection, as with chickens and foals, it transmits the habit in
+wonderful perfection and at a remarkably early date. It transmits new
+paces in horses in a single generation, but fails to perpetuate the
+songs of birds. It modifies offspring like parents, and yet allows the
+formation of two reproductive types in plants, and of two or more types
+widely different from the parents in some of the higher insects. It is
+said to be indispensable for the co-ordinated development of man and the
+giraffe and the elk, but appears to be unnecessary for the evolution and
+the maintenance of wonderful structures and habits and instincts in a
+thousand species of ants and bees and termites. It is the only possible
+means of complex evolution and adaptation of co-operative parts, and yet
+in Mr. Spencer's most representative case it renders such important
+parts as teeth and jaws unsuited for each other, and is said to ruin the
+teeth by the consequent overcrowding and decay. It survives amidst a
+general "lack of recognised evidence," and only seems to act usefully
+and healthily and regularly in quarters where it can least easily be
+distinguished from other more powerful and demonstrable factors of
+evolution. So little does it care to display its powers where they would
+be easily verifiable as well as useful that practical breeders ignore
+it. So slight is its independent power that it seems to allow natural
+selection or sexual selection or artificial selection to modify
+organisms in sheer defiance of its utmost opposition, just as readily as
+they modify organisms in other directions with its utmost help. If it
+partially perpetuates and extends the pecked-out indentations in the
+motmot's tail feathers, it on the other hand fails to transmit the
+slightest trace of mutilation in an almost infinite number of ordinary
+cases, and even where the mutilation is repeated for a hundred
+generations; and it apparently repairs rather than transmits the
+ordinary and oft-repeated losses caused by plucking hair, down and
+feathers, and the wear and tear of claws, teeth, hoofs and skin.
+
+It is often mischievous as well as anomalous in its action. Under
+civilization with its division of labour, the various functions of mind
+and body are very unequally exercised. There is overwork or misuse of
+one part and disuse and neglect of others, leading to the partial
+breakdown or degeneration of various organs and to general deterioration
+of health through disturbed balance of the constitution. The brain, or
+rather particular parts of it, are often over-stimulated, while the body
+is neglected. In many ways education and civilization foster nervousness
+and weakness, and undermine the rude natural health and spirits of the
+human animal. Alcohol, tobacco, tea, coffee, extra brain work, late
+hours, dissipation, overwork, indoor life, division of labour,
+preservation of the weak, and many other causes, all help to injure the
+modern constitution; so that the prospect of cumulative intensification
+of these evils by the additional influence of use-inheritance is not an
+encouraging one. It is true that modern progress and prosperity are
+improving the people in various respects by their direct action; but if
+use-inheritance has any share in effecting this improvement it must also
+transmit increased wants and more luxurious habits, together with such
+evils as have already been referred to. As depicted by its defenders,
+use-inheritance transmits evils far more powerfully and promptly than
+benefits. It transmits insanity and shattered nerves rather than the
+healthy brain which preceded the breakdown. It perpetuates, and
+cumulatively intensifies, a deterioration in the senses of civilized
+men, but it fails to perpetuate the rank vigour of various plants when
+too well nourished, or the flourishing condition of various animals when
+too fat or when tamed. It already transmits the short-sight caused by so
+modern an art as watchmaking, but so fails to transmit the
+long-practised art of seeing (as it does of walking and talking) that
+vision is worse than useless to a man until he gradually acquires the
+necessary but non-transmitted associations of sensation and idea by his
+own experience. In a well-known case, a blind man on gaining his sight
+by an operation said that "all objects seemed to touch his eyes, as what
+he felt did his skin"--so little had the universal experience of
+countless ages impressed itself on his faculties. Under normal healthy
+conditions use-inheritance is so slow in its action that "several
+generations" must elapse before it produces any appreciable effect, and
+then that effect is only precisely what selection might be expected to
+bring about without its aid. Strong for evil and slow for good, it can
+convey epilepsy promptly in guinea pigs, but transmits the acquirements
+of genius so poorly that our best student of the heredity of genius has
+to account for the frequent and remarkable deterioration of the
+offspring by a theory which is strongly hostile to use-inheritance. It
+would tend to make organisms unworkable by the excessive differences in
+its rate and manner of action on co-operative parts, and by adapting
+these parts to the total amount of nourishment received rather than to
+occasional necessity or actual usefulness. It would tend to stereotype
+habits and convert reason into instinct.
+
+How then can we rely upon use-inheritance for the improvement of the
+race? Even if it is not a sheer delusion, it may be more detrimental as
+a positive evil than it is advantageous as an unnecessary benefit; and
+as a normal modifying agent it is miserably weak and untrustworthy in
+comparison with the powerful selective influences by which nature and
+society continually and inevitably affect the species for good or for
+evil. The effects of use and disuse--rightly directed by education in
+its widest sense--must of course be called in to secure the highly
+essential but nevertheless _superficial, limited, and partly deceptive_
+improvement of individuals and of social manners and methods; but as
+this artificial development of already existing potentialities does not
+directly or readily tend to become congenital, it is evident that some
+considerable amount of natural or artificial selection of the more
+favourably varying individuals will still be the only means of securing
+the race against the constant tendency to degeneration which would
+ultimately swallow up all the advantages of civilization. The selective
+influences by which our present high level has been reached and
+maintained may well be modified, but they must not be abandoned or
+reversed in the rash expectation that State education, or State feeding
+of children, or State housing of the poor, or any amount of State
+socialism or public or private philanthropy, will prove permanently
+satisfactory substitutes. If ruinous deterioration and other more
+immediate evils, are to be avoided, the race must still be to the swift
+and the battle to the strong. The healthy Individualism so earnestly
+championed by Mr. Spencer must be allowed free play. Open competition,
+as Darwin teaches, with its survival and multiplication of the fittest,
+must be allowed to decide the battle of life independently of a foolish
+benevolence that prefers the elaborate cultivation and multiplication of
+weeds to the growth of corn and roses. We are trustees for the countless
+generations of the future. If we are wise we shall trust to the great
+ruling truths that we assuredly know, rather than to the seductive
+claims of an alleged factor of evolution for which no satisfactory
+evidence can be produced.
+
+
+THE END.
+
+RICHARD CLAY AND SONS, LIMITED, LONDON AND BUNGAY.
+
+
+FOOTNOTES:
+
+[72] Professor Romanes had casts made of the feet of upland geese, and
+could not detect any diminution as compared with the web of other geese
+in relation to the toes.
+
+
+
+
+NATURE SERIES.
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+By Sir WILLIAM THOMSON, D.C.L. LL.D., F.R.S.E, Fellow of St. Peter's
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+CHARLES DARWIN. Memorial Notices reprinted from _Nature_. By THOMAS
+HENRY HUXLEY, F.R.S.; G. J. ROMANES, F.R.S.; ARCHIBALD GEIKIE, F.R.S.;
+and W. T. THISELTON DYER, F.R.S. With a Portrait engraved by C. H.
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+ON THE COLOURS OF FLOWERS. As Illustrated in the British Flora. By GRANT
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+THE SCIENTIFIC EVIDENCES OF ORGANIC EVOLUTION. By GEORGE J. ROMANES,
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+The Project Gutenberg EBook of Are the Effects of Use and Disuse Inherited?, by 
+William Platt Ball
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Are the Effects of Use and Disuse Inherited?
+       An Examination of the View Held by Spencer and Darwin
+
+Author: William Platt Ball
+
+Release Date: August 26, 2008 [EBook #26438]
+
+Language: English
+
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+*** START OF THIS PROJECT GUTENBERG EBOOK THE EFFECTS OF USE AND DISUSE ***
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+</pre>
+
+
+<div class="bk1">
+<div class="p1"><i>NATURE SERIES</i></div>
+
+<h1>ARE THE EFFECTS OF USE AND
+DISUSE INHERITED?</h1>
+
+<div class="p5"><i><big>AN EXAMINATION OF THE VIEW HELD BY<br />
+SPENCER AND DARWIN</big></i></div>
+
+<h2><span class="fss">BY</span><br />
+WILLIAM PLATT BALL</h2>
+
+<div class="p3"><big><b>London</b></big><br />
+<big>MACMILLAN AND CO.</big><br />
+<small>AND NEW YORK</small><br />
+<small>1890</small></div>
+
+<div class="p4"><i><small>The Right of Translation and Reproduction is Reserved</small></i></div>
+</div>
+
+<hr />
+
+<div class="center"><small><span class="smcap">Richard Clay and Sons, Limited,<br />
+London and Bungay.</span></small></div>
+
+<hr /><p><span class='pagenum'><a name="Page_v" id="Page_v">[v]</a></span></p>
+<h2>PREFACE.</h2>
+
+<p class="noin"><span class="smcap">My</span> warmest thanks are due to Mr. Francis
+Darwin, to Mr. E. B. Poulton (whose interest in
+the subject here discussed is shown by his share
+in the translation of Weismann's <i>Essays on
+Heredity</i>), and to Professor Romanes, for the help
+afforded by their kindly suggestions and criticisms,
+and for the advice and recommendation under
+which this essay is now published. Encouragement
+from Mr. Francis Darwin is to me the more
+precious, and the more worthy of grateful recognition,
+from the fact that my general conclusion
+that acquired characters are <i>not</i> inherited is<span class='pagenum'><a name="Page_vi" id="Page_vi">[vi]</a></span>
+at variance with the opinion of his revered father,
+who aided his great theory by the retention of
+some remains of Lamarck's doctrine of the inherited
+effect of habit. I feel as if the son, as
+representative of his great progenitor, were carrying
+out the idea of an appreciative editor who
+writes to me: "We must say that if Darwin were
+still alive, he would find your arguments of great
+weight, and undoubtedly would give to them the
+serious consideration which they deserve." I
+hope, then, that I may be acquitted of undue
+presumption in opposing a view sanctioned by
+the author of the <i>Origin of Species</i>, but already
+stoutly questioned and firmly rejected by such
+followers of his as Weismann, Wallace, Poulton,
+Ray Lankester, and others, to say nothing of its
+practical rejection by so great an authority on
+heredity as Francis Galton.</p>
+
+<p>The sociological importance of the subject has
+already been insisted on in emphatic terms by<span class='pagenum'><a name="Page_vii" id="Page_vii">[vii]</a></span>
+Mr. Herbert Spencer, and this importance may
+be even greater than he imagined.</p>
+
+<p>Civilization largely sets aside the harsh but
+ultimately salutary action of the great law of
+Natural Selection without providing an efficient
+substitute for preventing degeneracy. The substitute
+on which moralists and legislators rely&mdash;if
+they think on the matter at all&mdash;is the
+cumulative inheritance of the beneficial effects of
+education, training, habits, institutions, and so
+forth&mdash;the inheritance, in short, of acquired
+characters, or of the effects of use and disuse.
+If this substitute is but a broken reed, then the
+deeper thinkers who gradually teach the teachers
+of the people, and ultimately even influence the
+legislators and moralists, must found their
+systems of morality and their criticisms of social
+and political laws and institutions and customs
+and ideas on the basis of the Darwinian law
+rather than on that of Lamarck.<span class='pagenum'><a name="Page_viii" id="Page_viii">[viii]</a></span></p>
+
+<p>Looking forward to the hope that the human
+race may become consciously and increasingly
+master of itself and of its destiny, and recognizing
+the Darwinian principle of the selection
+of the fittest as the <i>only</i> means of preventing the
+moral and physical degeneracy which, like an internal
+dry rot, has hitherto been the besetting
+danger of all civilizations, I desire that the
+thinkers who mould the opinions of mankind shall
+not be led astray from the true path of enduring
+progress and happiness by reliance on fallacious
+beliefs which will not bear examination. Such, at
+least, is the feeling or motive which has prompted
+me to devote much time and thought to a difficult
+but important inquiry in a debatable region of
+inference and conjecture, where (I am afraid)
+evidence on either side can never be absolutely
+conclusive, and where, especially, the absolute
+demonstration of a universal negative cannot
+reasonably be expected.</p>
+
+<hr /><p><span class='pagenum'><a name="Page_ix" id="Page_ix">[ix]</a></span></p>
+<h2>CONTENTS.</h2>
+
+<div class='center'>
+<table border="0" cellpadding="1" cellspacing="0" summary="">
+<tr><td class="td1">PREFACE</td><td class="td2"><small>PAGE</small><br /><a href="#Page_v">v</a></td></tr>
+<tr><td class="td1">IMPORTANCE AND BEARING OF THE INQUIRY</td><td class="td2"><a href="#Page_1">1</a></td></tr>
+<tr><td class="td1">SPENCER'S EXAMPLES AND ARGUMENTS</td><td class="td2"><a href="#Page_6">6-44</a></td></tr>
+<tr><td class="td3">Diminution of the Jaws</td><td class="td2"><a href="#Page_6">6</a></td></tr>
+<tr><td class="td3">Diminished Biting Muscles of Lap-Dogs</td><td class="td2"><a href="#Page_12">12</a></td></tr>
+<tr><td class="td3">Crowded Teeth</td><td class="td2"><a href="#Page_14">14</a></td></tr>
+<tr><td class="td3">Blind Cave-Crabs</td><td class="td2"><a href="#Page_17">17</a></td></tr>
+<tr><td class="td3">No Concomitant Variation from Concomitant Disuse</td><td class="td2"><a href="#Page_17">17</a></td></tr>
+<tr><td class="td3">The Giraffe, and Necessity for Concomitant Variation</td><td class="td2"><a href="#Page_18">18</a></td></tr>
+<tr><td class="td3">Alleged Ruinous Effects of Natural Selection</td><td class="td2"><a href="#Page_23">23</a></td></tr>
+<tr><td class="td3">Adverse Case of Neuter Insects</td><td class="td2"><a href="#Page_24">24</a></td></tr>
+<tr><td class="td3">&AElig;sthetic Faculties</td><td class="td2"><a href="#Page_29">29</a></td></tr>
+<tr><td class="td3">Lack of Evidence</td><td class="td2"><a href="#Page_34">34</a><span class='pagenum'><a name="Page_x" id="Page_x">[x]</a></span></td></tr>
+<tr><td class="td3">Inherited Epilepsy in Guinea-Pigs</td><td class="td2"><a href="#Page_35">35</a></td></tr>
+<tr><td class="td3">Inherited Insanity and Nervous Disorders</td><td class="td2"><a href="#Page_36">36</a></td></tr>
+<tr><td class="td3">Individual and Transmissible Type not Modified Alike</td><td class="td2"><a href="#Page_40">40</a></td></tr>
+<tr><td class="td1">DARWIN'S EXAMPLES</td><td class="td2"><a href="#Page_45">45-100</a></td></tr>
+<tr><td class="td3">Reduced Wings of Birds of Oceanic Islands</td><td class="td2"><a href="#Page_49">49</a></td></tr>
+<tr><td class="td3">Drooping Ears and Deteriorated Instincts</td><td class="td2"><a href="#Page_53">53</a></td></tr>
+<tr><td class="td3">Wings and Legs of Ducks and Fowls</td><td class="td2"><a href="#Page_55">55</a></td></tr>
+<tr><td class="td3">Pigeons' Wings</td><td class="td2"><a href="#Page_62">62</a></td></tr>
+<tr><td class="td3">Shortened Breast-Bone in Pigeons</td><td class="td2"><a href="#Page_64">64</a></td></tr>
+<tr><td class="td3">Shortened Feet in Pigeons</td><td class="td2"><a href="#Page_70">70</a></td></tr>
+<tr><td class="td3">Shortened Legs of Rabbits</td><td class="td2"><a href="#Page_70">70</a></td></tr>
+<tr><td class="td3">Blind Cave-Animals</td><td class="td2"><a href="#Page_72">72</a></td></tr>
+<tr><td class="td3">Inherited Habits</td><td class="td2"><a href="#Page_73">73</a></td></tr>
+<tr><td class="td3">Tameness of Rabbits</td><td class="td2"><a href="#Page_76">76</a></td></tr>
+<tr><td class="td3">Modifications Obviously Attributable to Selection</td><td class="td2"><a href="#Page_82">82</a></td></tr>
+<tr><td class="td3">Similar Effects of Natural Selection and Use-Inheritance</td><td class="td2"><a href="#Page_83">83</a></td></tr>
+<tr><td class="td3">Inferiority of Senses in Europeans</td><td class="td2"><a href="#Page_85">85</a></td></tr>
+<tr><td class="td3">Short-Sight in Watchmakers and Engravers</td><td class="td2"><a href="#Page_85">85</a></td></tr>
+<tr><td class="td3">Larger Hands of Labourers' Infants</td><td class="td2"><a href="#Page_87">87</a></td></tr>
+<tr><td class="td3">Thickened Sole in Infants</td><td class="td2"><a href="#Page_88">88</a></td></tr>
+<tr><td class="td3">A Source of Mental Confusion</td><td class="td2"><a href="#Page_91">91</a><span class='pagenum'><a name="Page_xi" id="Page_xi">[xi]</a></span></td></tr>
+<tr><td class="td3">Weakness of Use-Inheritance</td><td class="td2"><a href="#Page_94">94</a></td></tr>
+<tr><td class="td1">INHERITED INJURIES</td><td class="td2"><a href="#Page_101">101-118</a></td></tr>
+<tr><td class="td3">Inherited Mutilations</td><td class="td2"><a href="#Page_101">101</a></td></tr>
+<tr><td class="td3">The Motmot's Tail</td><td class="td2"><a href="#Page_110">110</a></td></tr>
+<tr><td class="td3">Other Inherited Injuries Mentioned by Darwin</td><td class="td2"><a href="#Page_111">111</a></td></tr>
+<tr><td class="td3">Quasi-Inheritance</td><td class="td2"><a href="#Page_116">116</a></td></tr>
+<tr><td class="td1">MISCELLANEOUS CONSIDERATIONS</td><td class="td2"><a href="#Page_119">119-143</a></td></tr>
+<tr><td class="td3">True Relation of Parents and Offspring</td><td class="td2"><a href="#Page_119">119</a></td></tr>
+<tr><td class="td3">Inverse Inheritance</td><td class="td2"><a href="#Page_123">123</a></td></tr>
+<tr><td class="td3">Early Origin of the Ova</td><td class="td2"><a href="#Page_124">124</a></td></tr>
+<tr><td class="td3">Marked Effects of Use and Disuse on the Individual</td><td class="td2"><a href="#Page_126">126</a></td></tr>
+<tr><td class="td3">Would Natural Selection Favour Use-Inheritance?</td><td class="td2"><a href="#Page_127">127</a></td></tr>
+<tr><td class="td3">Use-Inheritance an Evil</td><td class="td2"><a href="#Page_128">128</a></td></tr>
+<tr><td class="td3">Varied Effects of Use and Disuse</td><td class="td2"><a href="#Page_134">134</a></td></tr>
+<tr><td class="td3">Use-Inheritance Implies Pangenesis</td><td class="td2"><a href="#Page_137">137</a></td></tr>
+<tr><td class="td3">Pangenesis Improbable</td><td class="td2"><a href="#Page_138">138</a></td></tr>
+<tr><td class="td3">Spencer's Explanation of Use-Inheritance</td><td class="td2"><a href="#Page_141">141</a></td></tr>
+<tr><td class="td1">CONCLUSIONS</td><td class="td2"><a href="#Page_144">144-156</a><span class='pagenum'><a name="Page_xii" id="Page_xii">[xii]</a></span></td></tr>
+<tr><td class="td3">Use-Inheritance Discredited as Unnecessary, Unproven, and Improbable</td><td class="td2"><a href="#Page_144">144</a></td></tr>
+<tr><td class="td3">Modern Reliance on Use-Inheritance Misplaced</td><td class="td2"><a href="#Page_145">145</a></td></tr>
+</table></div>
+
+<hr /><p><span class='pagenum'><a name="Page_1" id="Page_1">[1]</a></span></p>
+<h1>ARE THE EFFECTS OF USE AND DISUSE INHERITED?</h1>
+
+<h2>IMPORTANCE AND BEARING OF THE INQUIRY.</h2>
+
+<p class="noin"><span class="smcap">The</span> question whether the effects of use and
+disuse are inherited, or, in other words, whether
+acquired characters are hereditary, is of considerable
+interest to the general student of
+evolution; but it is, or should be, a matter of
+far deeper interest to the thoughtful philanthropist
+who desires to ensure the permanent
+welfare and happiness of the human race. So<span class='pagenum'><a name="Page_2" id="Page_2">[2]</a></span>
+profoundly important, in fact, are the moral,
+social, and political conclusions that depend on
+the answer to this inquiry, that, as Mr. Herbert
+Spencer rightly says, it "demands, beyond all
+other questions whatsoever, the attention of
+scientific men."</p>
+
+<p>It is obvious that we can produce important
+changes in the individual. We can, for example,
+improve his muscles by athletics, and his brain
+by education. The use of organs enlarges and
+strengthens them; the disuse of parts or faculties
+weakens them. And so great is the power of habit
+that it is proverbially spoken of as "second
+nature." It is thus certain that we can modify
+the individual. We can strengthen (or weaken)
+his body; we can improve (or deteriorate) his
+intellect, his habits, his morals. But there
+remains the still more important question which
+we are about to consider. Will such modifications
+be inherited by the offspring of the<span class='pagenum'><a name="Page_3" id="Page_3">[3]</a></span>
+modified individual? Does individual improvement
+transmit itself to descendants independently
+of personal teaching and example? Have
+artificially produced changes of structure or habit
+any inherent tendency to become congenitally
+transmissible and to be converted in time into
+fixed traits of constitution or character? Can the
+philanthropist rely on such a tendency as a hopeful
+factor in the evolution of mankind?&mdash;the only
+sound and stable basis of a higher and happier
+state of things being, as he knows or ought to
+know, the innate and constitutionally-fixed improvement
+of the race as a whole. If acquired
+modifications are impressed on the offspring and
+on the race, the systematic moral training of
+individuals will in time produce a constitutionally
+moral race, and we may hope to improve mankind
+even in defiance of the unnatural selection by which
+a spurious but highly popular philanthropy would
+systematically favour the survival of the unfittest<span class='pagenum'><a name="Page_4" id="Page_4">[4]</a></span>
+and the rapid multiplication of the worst.
+But if acquired modifications do not tend to be
+transmitted, if the use or disuse of organs
+or faculties does not similarly affect posterity
+by inheritance, then it is evident that no
+innate improvement in the race can take
+place without the aid of natural or artificial
+selection.</p>
+
+<p>Herbert Spencer maintains that the effects of
+use and disuse <i>are</i> inherited in kind, and in his
+<i>Factors of Organic Evolution</i><a name="FNanchor_1_1" id="FNanchor_1_1"></a><a href="#Footnote_1_1" class="fnanchor">[1]</a> he has supported
+his contention with a selection of facts and reasonings
+which I shall have the temerity to examine
+and criticize. Darwin also held the same view,
+though not so strongly. And here, to prevent
+misunderstanding, I may say that the admiration
+and reverence and gratitude due to Darwin ought
+not to be allowed to interfere in the slightest<span class='pagenum'><a name="Page_5" id="Page_5">[5]</a></span>
+degree with the freest criticism of his conclusions.
+To perfect his work by the correction of
+really extraneous errors is as much a sacred duty
+as to study and apply the great truths he has
+taught.</p>
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote"><p><a name="Footnote_1_1" id="Footnote_1_1"></a><a href="#FNanchor_1_1"><span class="label">[1]</span></a> Which originally appeared in the <i>Nineteenth Century</i> for April
+and May, 1886.</p></div>
+</div>
+
+<hr /><p><span class='pagenum'><a name="Page_6" id="Page_6">[6]</a></span></p>
+<h2>SPENCER'S EXAMPLES AND ARGUMENTS.</h2>
+
+<h3>DIMINUTION OF THE JAWS IN CIVILIZED RACES.</h3>
+
+<p class="noin"><span class="smcap">Mr. Spencer</span> verified this by comparing English
+jaws with Australian and Negro jaws at the College
+of Surgeons.<a name="FNanchor_2_2" id="FNanchor_2_2"></a><a href="#Footnote_2_2" class="fnanchor">[2]</a> He maintains that the diminution
+of the jaw in civilized races can <i>only</i> have been<span class='pagenum'><a name="Page_7" id="Page_7">[7]</a></span>
+brought about by inheritance of the effects of
+lessened use. But if English jaws are lighter
+and thinner than those of Australians and
+Negroes, so too is the rest of the skull. As
+the diminution in the weight and thickness of
+the walls of the cranium cannot well be ascribed
+to disuse, it must be attributed to some other
+cause; and this cause may have affected the jaw
+also. Cessation of the process by which natural
+selection<a name="FNanchor_3_3" id="FNanchor_3_3"></a><a href="#Footnote_3_3" class="fnanchor">[3]</a> favoured strong thick bones during
+ages of brutal violence might bring about a
+change in this direction. Lightness of structure,
+facilitating agility and being economical of
+material, would also be favoured by natural
+selection so far as strength was not too
+seriously diminished.</p>
+
+<p><span class='pagenum'><a name="Page_8" id="Page_8">[8]</a></span></p><p>Sexual selection powerfully affects the human
+face, and so must affect the jaws&mdash;as is shown by
+the differences between male and female jaws,
+and by the relative lightness and smallness of
+the latter, especially in the higher races. Human
+preference, both sexual and social, would tend
+to eliminate huge jaws and ferocious teeth when
+these were no longer needed as weapons of war
+or organs of prehension, &amp;c. We can hardly
+assume that the lower half of the face is specially
+exempt from the influence of natural and sexual
+selection; and the effects of these undoubted
+factors of evolution must be fully considered
+before we are entitled to call in the aid of a
+factor whose existence is questioned.</p>
+
+<p>After allowing for lost teeth and the consequent
+alveolar absorption, and for a reduction
+proportional to that shown in the rest of the
+skull, the difference in average weight in fifty
+European and fourteen Australian male jaws<span class='pagenum'><a name="Page_9" id="Page_9">[9]</a></span>
+at the College of Surgeons turned out to be
+less than a fifth of an ounce, or about
+5 per cent. This slight reduction may be
+much more than accounted for by such causes
+as disuse in the individual, human preference
+setting back the teeth, and partial transference
+of the much more marked diminution seen in
+female jaws. There is apparently no room for
+accumulated <i>inherited</i> effects of ancestral disuse.
+The number of jaws is small, indeed; but weighing
+them is at least more decisive than Mr.
+Spencer's mere inspection.</p>
+
+<p>The differences between Anglo-Saxon male
+jaws and Australian and Tasmanian jaws are
+most easily explained as effects of human preference
+and natural selection. We can hardly
+suppose that disuse would maintain or develop
+the projecting chin, increase its perpendicular
+height till the jaw is deepest and strongest at
+its extremity, evolve a side flange, and enlarge<span class='pagenum'><a name="Page_10" id="Page_10">[10]</a></span>
+the upper jaw-bone to form part of a more
+prominent nose, while drawing back the savagely
+obtrusive teeth and lips to a more pleasing
+and subdued position of retirement and of
+humanized beauty. If human preference and
+natural selection caused some of these differences,
+why are they incompetent to effect changes in
+the direction of a diminution of the jaw or teeth?
+And if use and disuse are the sole modifying
+agents in the case of the human jaw, why
+should men have any more chin than a gorilla
+or a dog?</p>
+
+<p>The excessive weight of the West African jaws
+at the College of Surgeons is partly <i>against</i>
+Mr. Spencer's contention, unless he assumes that
+Guinea Negroes use their jaws far more than the
+Australians, a supposition which seems extremely
+improbable. The heavier skull and narrower
+molar teeth point however to other factors than
+increased use.<span class='pagenum'><a name="Page_11" id="Page_11">[11]</a></span></p>
+
+<p>The striking variability of the human jaw is
+strongly opposed to the idea of its being under
+the direct and dominant control of so uniform a
+cause as ancestral use and disuse. Mr. Spencer
+regards a variation of 1 oz. as a large one, but I
+found that the English jaws in the College of
+Surgeons varied from 1&middot;9 oz. to 4&middot;3 oz. (or 5 oz.
+if lost teeth were allowed for); Australian jaws
+varied from 2 oz. to 4&middot;5 oz. (with <i>no</i> lost teeth to
+allow for); while in Negro jaws the maximum
+rose to over 5&frac12; oz.<a name="FNanchor_4_4" id="FNanchor_4_4"></a><a href="#Footnote_4_4" class="fnanchor">[4]</a> In spite of disuse some
+European jaws were twice as heavy as the lightest
+Australian jaw, either absolutely or (in some
+cases) relatively to the cranium. The uniformity
+of change relied upon by Mr. Spencer is scarcely
+borne out by the facts so far as male jaws are
+concerned. The great reduction in the weight
+of <i>female</i> jaws <i>and skulls</i> evidently points to<span class='pagenum'><a name="Page_12" id="Page_12">[12]</a></span>
+sexual selection and to panmixia under male
+protection.</p>
+
+<p>I think, on the whole, we must conclude that
+the human jaws do not afford satisfactory proof
+of the inheritance of the effects of use and disuse,
+inasmuch as the differences in their weight and
+shape and size can be more reasonably and consistently
+accounted for as the result of less
+disputable causes.</p>
+
+<h3>DIMINISHED BITING MUSCLES OF LAP-DOGS.</h3>
+
+<p>The next example, the reduced biting muscles,
+&amp;c., of lap-dogs is also unsatisfactory as a proof
+of the inheritance of the effects of disuse; for
+the change can readily be accounted for without
+the introduction of such a factor. The previous
+natural selection of strong jaws and teeth and
+muscles is reversed. The conscious or unconscious
+selection of lap-dogs with the least tendency to<span class='pagenum'><a name="Page_13" id="Page_13">[13]</a></span>
+bite would easily bring about a general enfeeblement
+of the whole biting apparatus&mdash;weakness
+of the parts concerned favouring harmlessness.
+Mr. Spencer maintains that the dwindling of the
+parts concerned in clenching the jaw is certainly
+not due to artificial selection because the modifications
+offer no appreciable external signs. Surely
+hard biting is sufficiently appreciable by the
+person bitten without any visual admeasurement
+of the masseter muscles or the zygomatic arches.
+Disuse during lifetime would also cause some
+amount of degeneracy; and I am not sure that
+Mr. Spencer is right in <i>entirely</i> excluding economy
+of nutrition from the problem. Breeders would
+not over-feed these dogs; and the puppies that
+grew most rapidly would usually be favoured.</p>
+
+<p><span class='pagenum'><a name="Page_14" id="Page_14">[14]</a></span></p>
+<h3>CROWDED TEETH.</h3>
+
+<p>The too closely-packed teeth in the "decreasing"
+jaws of modern men (p. 13)<a name="FNanchor_5_5" id="FNanchor_5_5"></a><a href="#Footnote_5_5" class="fnanchor">[5]</a> are also suggestive
+of other causes than use and disuse. Why is there
+not simultaneous variation in teeth and jaws, if
+disuse is the governing factor? Are we to suppose
+that the size of the human teeth is maintained
+by use at the same time that the jaws are being
+diminished by disuse? Mr. Spencer acknowledges
+that the crowding of bull-dogs' and lap-dogs'
+teeth is caused by the artificial selection of shortened
+jaws. If a similar change is really occurring in
+man, could it not be similarly explained by some
+factor, such as sexual selection, which might
+affect the outward appearance at the cost of
+less obvious defects or inconveniences?</p>
+
+<p>Mr. Spencer points to the decay of modern teeth
+as a sign or result of their being overcrowded<span class='pagenum'><a name="Page_15" id="Page_15">[15]</a></span>
+through the diminution of the jaw by disuse.<a name="FNanchor_6_6" id="FNanchor_6_6"></a><a href="#Footnote_6_6" class="fnanchor">[6]</a>
+But the teeth which are the most frequently overcrowded
+are the lower incisors. The upper incisors
+are less overcrowded, being commonly pressed
+outwards by the lower arc of teeth fitting inside
+them in biting. The lower incisors are correspondingly
+pressed inwards and closer together. Yet the
+upper incisors decay&mdash;or at least are extracted&mdash;about
+twenty times as frequently as the closely
+packed lower incisors.<a name="FNanchor_7_7" id="FNanchor_7_7"></a><a href="#Footnote_7_7" class="fnanchor">[7]</a> Surely this must indicate
+that the cause of decay is not overcrowding.</p>
+
+<p><span class='pagenum'><a name="Page_16" id="Page_16">[16]</a></span></p><p>The lateness and irregularity of the wisdom teeth
+are sometimes supposed to indicate their gradual
+disappearance through want of room in a diminishing
+jaw. But a note on Tasmanian skulls in the
+<i>Catalogue of the College of Surgeons</i> (p. 199) shows
+that this lateness and irregularity have been common
+among Tasmanians as well as among civilized
+races, so that the change can hardly be attributed
+to the effects of disuse under civilization.</p>
+
+<p><span class='pagenum'><a name="Page_17" id="Page_17">[17]</a></span></p>
+<h3>BLIND CAVE-CRABS.</h3>
+
+<p>The cave-crabs which have lost their disused
+eyes but <i>not the disused eye-stalks</i> appear to illustrate
+the effects of natural selection rather than
+of disuse. The loss of the exposed, sensitive, and
+worse-than-useless eye, would be a decided gain,
+while the disused eye-stalk, being no particular
+detriment to the crab, would be but slightly
+affected by natural selection, though open to the
+cumulative effects of disuse. The disused but
+better protected eyes of the blind cave-rat are
+still "of large size" (<i>Origin of Species</i>, p. 110).</p>
+
+<h3>NO CONCOMITANT VARIATION FROM
+CONCOMITANT DISUSE.</h3>
+
+<p>It is but fair to add that these instances of the
+cave-crab's eye-stalk and the closely-packed teeth
+are put forward by Mr. Spencer with the more<span class='pagenum'><a name="Page_18" id="Page_18">[18]</a></span>
+immediate object of proving that there is "no
+concomitant variation in co-operative parts," even
+when "formed out of the same tissue, like the
+crab's eye and its peduncle" (pp. 12-14, 23, 33).
+It escapes his notice, however, that in two out
+of his three cases it is <i>disuse</i>, or <i>diminished
+use</i>, which fails to cause concomitant variation or
+proportionate variation.</p>
+
+<h3>THE GIRAFFE, AND NECESSITY FOR
+CONCOMITANT VARIATION.</h3>
+
+<p>Having unwittingly shown that lessened use of
+closely-connected and co-operative parts does not
+cause concomitant variation in these parts, Mr.
+Spencer concludes that the concomitant variation
+requisite for evolution can only be caused
+by altered degrees of use or disuse. He elaborately
+argues that the many co-ordinated modifications
+of parts necessitated by each important<span class='pagenum'><a name="Page_19" id="Page_19">[19]</a></span>
+alteration in an animal are so complex that they
+cannot possibly be brought about except by
+the inherited effect of the use and disuse of the
+various parts concerned. He holds, for instance,
+that natural selection is inadequate to effect
+the numerous concomitant changes necessitated
+by such developments as that of the long neck
+of the giraffe. Darwin, however, on the contrary,
+holds that natural selection alone "would have
+sufficed for the production of this remarkable
+quadruped."<a name="FNanchor_8_8" id="FNanchor_8_8"></a><a href="#Footnote_8_8" class="fnanchor">[8]</a> He is surprised at Mr. Spencer's
+view that natural selection can do so little in
+modifying the higher animals. Thus one of the
+chief arguments with which Mr. Spencer supports
+his theory is so poorly founded as to be rejected by
+a far greater authority on such subjects. All that
+is needed is that natural selection should preserve
+the tallest giraffes through times of famine by their<span class='pagenum'><a name="Page_20" id="Page_20">[20]</a></span>
+being able to reach otherwise inaccessible stores of
+foliage. The continual variability of all parts of
+the higher animals gives scope for innumerable
+changes, and Nature is not in a hurry. Mr.
+Spencer, however, says that "the chances against
+any adequate readjustments fortuitously arising
+must be infinity to one." But he has also shown
+that altered degree of use does not cause the
+needed concomitant variation of co-operative
+parts. So the chances against a beneficial change
+in an animal must be, at a liberal estimate, infinity
+to two. Mr. Spencer, if he has proved anything,
+has proved that it is practically impossible that
+the giraffe can have acquired a long neck, or the
+elk its huge horns, or that any species has ever
+acquired any important modification.</p>
+
+<p>Mr. Wallace, in his <i>Darwinism</i>, answers Mr.
+Spencer by a collection of facts showing that
+"variation is the rule," that the range of variation
+in wild animals and plants is much greater<span class='pagenum'><a name="Page_21" id="Page_21">[21]</a></span>
+than was supposed, and that "each part varies
+to a considerable extent independently" of other
+parts, so that "the materials constantly ready
+for natural selection to act upon are abundant in
+quantity and very varied in kind." While co-operative
+parts would often be more or less
+correlated, so that they would tend to vary together,
+coincident variation is not necessary. The
+lengthened wing might be gained in one generation,
+and the strengthened muscle at a subsequent
+period; the bird in the meanwhile drawing
+upon its surplus energy, aided (as I would suggest)
+by the strengthening effect of increased use in
+the individual. Seeing that artificial selection
+of complicated variations has modified animals
+in many points either simultaneously or by slow
+steps, as with otter-sheep, fancy pigeons, &amp;c.
+(many of the characters thus obtained being
+clearly independent of use and disuse), natural
+selection must be credited with similar powers,<span class='pagenum'><a name="Page_22" id="Page_22">[22]</a></span>
+and Mr. Wallace concludes that Mr. Spencer's
+insuperable difficulty is "wholly imaginary."</p>
+
+<p>The extract concerning a somewhat similar
+"class of difficulties," which Mr. Spencer quotes
+from his <i>Principles of Biology</i>, is faulty in its
+reasoning,<a name="FNanchor_9_9" id="FNanchor_9_9"></a><a href="#Footnote_9_9" class="fnanchor">[9]</a> though legitimate in its conclusion
+concerning the increasing difficulty of evolution
+in proportion with the increasing number and
+complexity of faculties to be evolved. But this
+increasing difficulty of complex evolution is only
+overcome by <i>some</i> favourably-varying individuals
+and species&mdash;not by all. And as the difficulty<span class='pagenum'><a name="Page_23" id="Page_23">[23]</a></span>
+increases we find neglect and decay of the less-needed
+faculties&mdash;as with domesticated animals
+and civilized men, who lose in one direction while
+they gain in another. The increasing difficulty
+of complex evolution by natural selection is no
+proof whatever of use-inheritance<a name="FNanchor_10_10" id="FNanchor_10_10"></a><a href="#Footnote_10_10" class="fnanchor">[10]</a> except to those
+who confound difficulty with impossibility.</p>
+
+<h3>ALLEGED RUINOUS EFFECTS OF NATURAL
+SELECTION.</h3>
+
+<p>Mr. Spencer further contends that natural selection,
+by unduly developing specially advantageous
+modifications without the necessary but complex
+secondary modifications, would render the constitution<span class='pagenum'><a name="Page_24" id="Page_24">[24]</a></span>
+of a variety "unworkable" (p. 23). But this
+seems hardly feasible, seeing that natural selection
+must continually favour the most workable constitutions,
+and will only preserve organisms in proportion
+as they combine general workableness
+with the special modification. On the other hand,
+according to Mr. Spencer himself, use-inheritance
+must often disturb the balance of the constitution.
+Thus it tends to make the jaws and teeth unworkable
+through the overcrowding and decay of the
+teeth&mdash;there being, as his illustrations show, no
+simultaneous or concomitant or proportional
+variation in relation to altered degree of use
+or disuse.</p>
+
+<h3>ADVERSE CASE OF NEUTER INSECTS.</h3>
+
+<p>Mr. Spencer also holds that most mental
+phenomena, especially where complex or social
+or moral, can only be explained as arising from<span class='pagenum'><a name="Page_25" id="Page_25">[25]</a></span>
+use-inheritance, which becomes more and more
+important as a factor of evolution as we advance
+from the vegetable world and the lower grades
+of animal life to the more complex activities,
+tastes, and habits of the higher organizations
+(preface, and p. 74). But there happens to be a
+tolerably clear proof that such changes as the
+evolution of complicated structures and habits
+and social instincts <i>can</i> take place independently
+of use-inheritance. The wonderful instincts of the
+working bees have apparently been evolved
+(at least in all their later social complications
+and developments) without the aid of use-inheritance&mdash;nay,
+in spite of its utmost opposition.
+Working bees, being infertile "neuters," cannot
+as a rule transmit their own modifications and
+habits. They are descended from countless
+generations of queen bees and drones, whose habits
+have been widely different from those of the
+workers, and whose structures are dissimilar in<span class='pagenum'><a name="Page_26" id="Page_26">[26]</a></span>
+various respects. In many species of ants there
+are two, and in the leaf-cutting ants of Brazil
+there are <i>three</i>, kinds of neuters which differ from
+each other and from their male and female
+ancestors "to an almost incredible degree."<a name="FNanchor_11_11" id="FNanchor_11_11"></a><a href="#Footnote_11_11" class="fnanchor">[11]</a> The
+soldier caste is distinguished from the workers
+by enormously large heads, very powerful mandibles,
+and "extraordinarily different" instincts.
+In the driver ant of West Africa one kind
+of neuter is three times the size of the other,<span class='pagenum'><a name="Page_27" id="Page_27">[27]</a></span>
+and has jaws nearly five times as long. In
+another case "the workers of one caste alone carry
+a wonderful sort of shield on their heads." One of
+the three neuter classes in the leaf-cutting ants
+has a single eye in the midst of its forehead.
+In certain Mexican and Australian ants some of
+the neuters have huge spherical abdomens, which
+serve as living reservoirs of honey for the use
+of the community. In the equally wonderful
+case of the termites, or so-called "white ants"
+(which belong, however, to an entirely different
+order of insect from the ants and bees) the neuters
+are blind and wingless, and are divided into
+soldiers and workers, each class possessing the
+requisite instincts and structures adapting it
+for its tasks. Seeing that natural selection can
+form and maintain the various structures and
+the exceedingly complicated instincts of ants and
+bees and wasps and termites in direct defiance
+of the alleged tendency to use-inheritance, surely<span class='pagenum'><a name="Page_28" id="Page_28">[28]</a></span>
+we may believe that natural selection, unopposed
+by use-inheritance, is equally competent for
+the work of complex or social or mental evolution
+in the many cases where the strong presumptive
+evidence cannot be rendered almost indisputable
+by the exceptional exclusion of the modified
+animal from the work of reproduction.</p>
+
+<p>Ants and bees seem to be capable of altering
+their habits and methods of action much as men
+do. Bees taken to Australia cease to store
+honey after a few years' experience of the mild
+winters. Whole communities of bees sometimes
+take to theft, and live by plundering hives, first
+killing the queen to create dismay among the
+workers. Slave ants attend devotedly to their
+captors, and fight against their own species.
+Forel reared an artificial ant-colony made up
+of five different and more or less hostile species.
+Why cannot a much more intelligent animal
+modify his habits far more rapidly and comprehensively<span class='pagenum'><a name="Page_29" id="Page_29">[29]</a></span>
+without the aid of a factor which is
+clearly unnecessary in the case of the more
+intelligent of the social insects?</p>
+
+<h3>&AElig;STHETIC FACULTIES.</h3>
+
+<p>The modern development of music and harmony
+(p. 19) is undeniable, but why could it only
+have been brought about by the help of the
+inheritance of the effects of use? Why are
+we to suppose that "minor traits" such as the
+"&aelig;sthetic perceptions" cannot have been evolved
+by natural selection (p. 20) or by sexual selection?
+Darwin holds that our musical faculties
+were developed by sexual preference long before
+the acquisition of speech. He believes that the
+"rhythms and cadences of oratory are derived
+from previously developed musical powers"&mdash;a
+conclusion "exactly opposite" to that arrived at<span class='pagenum'><a name="Page_30" id="Page_30">[30]</a></span>
+by Mr. Spencer.<a name="FNanchor_12_12" id="FNanchor_12_12"></a><a href="#Footnote_12_12" class="fnanchor">[12]</a> The emotional susceptibility
+to music, and the delicate perceptions needed for
+the higher branches of art, were apparently the
+work of natural and sexual selection in the long
+past. Civilization, with its leisure and wealth
+and accumulated knowledge, perfects human
+faculties by artificial cultivation, develops and
+combines means of enjoyment, and discovers
+unsuspected sources of interest and pleasure.
+The sense of harmony, modern as it seems to be,
+must have been a latent and indirect consequence
+of the development of the sense of hearing and of
+melody. Use, at least, could never have called
+it into existence. Nature favours and develops
+enjoyments to a certain extent, for they subserve
+self-preservation and sexual and social preference
+in innumerable ways. But modern &aelig;sthetic advance
+seems to be almost entirely due to the culture
+of latent abilities, the formation of complex<span class='pagenum'><a name="Page_31" id="Page_31">[31]</a></span>
+associations, the selection and encouragement of
+talent, and the wide diffusion and imitation of the
+accumulated products of the well-cultivated genius
+of favourably varying individuals. The fact
+that uneducated persons do not enjoy the higher
+tastes, and the rapidity with which such tastes are
+acquired or professed, ought to be sufficient proof
+that modern culture is brought about by far
+swifter and more potent influences than use-inheritance.
+Neither would this hypothetical
+factor of evolution materially aid in explaining
+the many other rapid changes of habit brought
+about by education, custom, and the changed conditions
+of civilization generally. Powerful tastes&mdash;as
+is incontestably shown in the cases of alcohol and
+tobacco&mdash;lie latent for ages, and suddenly become
+manifest when suitable conditions arise. Every
+discovery, and each step in social and moral evolution,
+produces its wide-spreading train of consequences.
+I see no reason why use-inheritance<span class='pagenum'><a name="Page_32" id="Page_32">[32]</a></span>
+need be credited with any share in the cumulative
+results of the invention of printing and the
+steam-engine and gunpowder, or of freedom
+and security under representative government, or
+of science and art and the partial emancipation
+of the mind of man from superstition, or of the
+innumerable other improvements or changes that
+take place under modern civilization.</p>
+
+<p>Mr. Spencer suggests an inquiry whether the
+greater powers possessed by eminent musicians
+were not mainly due to the inherited effect of
+the musical practice of their fathers (p. 19).
+But these great musicians inherited far more than
+their parents possessed. The excess of their powers
+beyond their parents' must surely be attributed
+to spontaneous variation; and who shall say that
+the rest was in any way due to use-inheritance?
+If, too, the superiority of geniuses proves use-inheritance,
+why should not the inferiority of
+the sons of geniuses prove the existence of a<span class='pagenum'><a name="Page_33" id="Page_33">[33]</a></span>
+tendency which is the exact opposite of use-inheritance?
+But nobody collects facts concerning
+the degenerate branches of musical families.
+Only the favourably varying branches are noticed,
+and a general impression of rapid evolution of
+talent is thus produced. Such cases might be
+explained, too, by the facts that musical faculty
+is strong in both sexes, that musical families
+associate together, and that the more gifted members
+may intermarry. Great musicians are often
+astonishingly precocious. Meyerbeer "played
+brilliantly" at the age of six. Mozart played
+beautifully at four. Are we to suppose that the
+effect of the <i>adult</i> practice of parents was inherited
+at this early age? If use-inheritance was
+not necessary in the case of Handel, whose
+father was a surgeon, why is it needed to
+account for Bach?</p>
+
+<p><span class='pagenum'><a name="Page_34" id="Page_34">[34]</a></span></p>
+<h3>LACK OF EVIDENCE.</h3>
+
+<p>The "direct proofs" of use-inheritance are not
+as plentiful as might be desired, it appears (pp.
+24-28). This acknowledged "lack of recognized
+evidence" is indeed the weakest feature in the
+case, though Mr. Spencer would fain attribute this
+lack of direct proof to insufficient investigation
+and to the inconspicuous nature of the inheritance
+of the modification. But there is an almost
+endless abundance of conspicuous examples of
+the effects of use and disuse in the individual.
+How is it that the subsequent inheritance of these
+effects has not been more satisfactorily observed
+and investigated? Horse-breeders and others
+could profit by such a tendency, and one cannot
+help suspecting that the reason they ignore it
+must be its practical inefficacy, arising probably
+from its weakness, its obscurity and uncertainty
+or its non-existence.</p>
+
+<p><span class='pagenum'><a name="Page_35" id="Page_35">[35]</a></span></p>
+<h3>INHERITED EPILEPSY IN GUINEA-PIGS.</h3>
+
+<p>Brown-S&eacute;quard's discovery that an epileptic
+tendency artificially produced by mutilating the
+nervous system of a guinea-pig is occasionally
+inherited may be a fact of "considerable weight,"
+or on the other hand it may be entirely irrelevant.
+Cases of this kind strike one as peculiar exceptions
+rather than as examples of a general rule or law.
+They seem to show that certain morbid conditions
+may occasionally affect both the individual and
+the reproductive elements or transmissible type
+in a similar manner; but then we also know
+that such prompt and complete transmission
+of an artificial modification is widely different
+from the usual rule. Exceptional cases require
+exceptional explanations, and are scarcely good
+examples of the effect of a general tendency which
+in almost all other cases is so inconspicuous in
+its immediate effects. Further remarks on this<span class='pagenum'><a name="Page_36" id="Page_36">[36]</a></span>
+inherited epilepsy can be most conveniently
+introduced later on in connection with Darwin's
+explanation of the inherited mutilation which it
+usually accompanies, but which Mr. Spencer does
+not mention.</p>
+
+<h3>INHERITED INSANITY AND NERVOUS DISORDERS.</h3>
+
+<p>Mr. Spencer infers that, because insanity is
+usually hereditary, and insanity can be artificially
+produced by various excesses, therefore this artificially-produced
+insanity must also be hereditary
+(p. 28). Direct evidence of this conclusion would
+be better than a mere inference which may
+beg the very question at issue. That the liability
+to insanity commonly runs in families is no proof
+that strictly non-inherited insanity will subsequently
+become hereditary. I think that theories
+should be based on facts rather than facts on<span class='pagenum'><a name="Page_37" id="Page_37">[37]</a></span>
+theories, especially when those facts are to be
+the basis or proof of a further theory.</p>
+
+<p>Mr. Spencer also points out that he finds among
+physicians "the belief that nervous disorders
+of a less severe kind are inheritable"&mdash;a general
+belief which does not necessarily include the transmission
+of purely artificially-produced disorders,
+and so misses the point which is really at issue.
+He proceeds, however, to state more definitely
+that "men who have prostrated their nervous systems
+by prolonged overwork or in some other way,
+have children more or less prone to nervousness."
+The following observations will, I think, warrant
+at least a suspension of judgment concerning
+this particular form of use-inheritance.</p>
+
+<p>(1) The nervousness is seen in the <i>children</i> at
+an early age, although the nervous prostration
+from which it is supposed to be derived obviously
+occurs in the parent at a much later period of
+life. This change in time is contrary to the rule<span class='pagenum'><a name="Page_38" id="Page_38">[38]</a></span>
+of inheritance at corresponding periods; and,
+together with the unusual promptness and comparative
+completeness of the inheritance, it may
+indicate a special injury or deterioration of the
+reproductive elements rather than true inheritance.
+The healthy brain of early life has failed
+to transmit its robust condition. Is use-inheritance,
+then, only effective for evil? Does it only
+transfer the newly-acquired weakness, and not
+the previous long-continued vigour?</p>
+
+<p>(2) Members of nervous families would be liable
+to suffer from nervous prostration, and by the
+ordinary law of heredity alone would transmit
+nervousness to their children.</p>
+
+<p>(3) The shattered nerves or insanity resulting
+from alcoholic and other excesses, or from overwork
+or trouble, are evidently signs of a grave
+constitutional injury which may react upon the
+reproductive elements nourished and developed
+in that ruined constitution. The deterioration in<span class='pagenum'><a name="Page_39" id="Page_39">[39]</a></span>
+parent and child may often display itself in the
+same organs&mdash;those probably which are hereditarily
+weakest. Acquired diseases or disorders
+thus appear to be transmitted, when all that was
+conveyed to the offspring was the exciting cause
+of a lowered vitality or disordered action,
+together with the ancestral liability to such
+diseases under such conditions.</p>
+
+<p>(4) Francis Galton says that "it is hard to find
+evidence of the power of the personal structure
+to react upon the sexual elements, that is not
+open to serious objection." Some of the cases
+of apparent inheritance he regards as coincidence
+of effect. Thus "the fact that a drunkard will
+often have imbecile children, although his offspring
+previous to his taking to drink were healthy,"
+is an "instance of simultaneous action," and not
+of true inheritance. "The alcohol pervades his
+tissues, and, of course, affects the germinal
+matter in the sexual elements as much as it does<span class='pagenum'><a name="Page_40" id="Page_40">[40]</a></span>
+that in his own structural cells, which have led
+to an alteration in the quality of his own nerves.
+Exactly the same must occur in the case of
+many constitutional diseases that have been
+acquired by long-continued irregular habits."<a name="FNanchor_13_13" id="FNanchor_13_13"></a><a href="#Footnote_13_13" class="fnanchor">[13]</a></p>
+
+<h3>INDIVIDUAL AND TRANSMISSIBLE TYPE NOT
+MODIFIED ALIKE BY THE DIRECT EFFECT OF
+CHANGED HABITS OR CONDITIONS.</h3>
+
+<p>Mr. Spencer finds it hard to believe that the
+modifications conveyed to offspring are not identical
+in tendency with the changes effected in the
+parent by altered use or habit (pp. 23-25, 34).
+But it is perfectly certain that the two sets of
+effects do not necessarily correspond. The
+effect of changed habits or conditions on the
+individual is often very far from coinciding with
+the effects on the reproductive elements or the<span class='pagenum'><a name="Page_41" id="Page_41">[41]</a></span>
+transmissible type. The reproductive system is
+"extremely sensitive" to very slight changes,
+and is often powerfully affected by circumstances
+which otherwise have little effect on the individual
+(<i>Origin of Species</i>, p. 7). Various animals and
+plants become sterile when domesticated or supplied
+with too much nourishment. The native Tasmanians
+have already become extinct from sterility
+caused by greatly changed diet and habits. If,
+as Mr. Spencer teaches, continued culture and
+brain-work will in time produce lessened fertility
+or comparative sterility, we may yet have to be
+careful that intellectual development does not
+become a species of suicide, and that the
+culture of the race does not mean its extinction&mdash;or
+at least the extinction of those most
+susceptible of culture.</p>
+
+<p>The reproductive elements are also disturbed
+and modified in innumerable minor ways.
+Changed conditions or habits tend to produce<span class='pagenum'><a name="Page_42" id="Page_42">[42]</a></span>
+a general "plasticity" of type, the "indefinite
+variability" thus caused being apparently irrelevant
+to the change, if any, in the individual.<a name="FNanchor_14_14" id="FNanchor_14_14"></a><a href="#Footnote_14_14" class="fnanchor">[14]</a> A vast
+number of variations of structure have certainly
+arisen independently of similar parental modification
+as the preliminary. Whatever first caused
+these "spontaneous" congenital variations affected
+the reproductive elements quite differently from
+the individual. "When a new peculiarity first
+appears we can never predict whether it will be
+inherited." Many varieties of plants only keep
+true from shoots, and not from seed, which is by
+no means acted on in the same way as the
+individual plant. Seeing that such plants have<span class='pagenum'><a name="Page_43" id="Page_43">[43]</a></span>
+<i>two</i> reproductive types, both constant, it is evident
+that these cannot both be modified in the
+same way as the parent is modified. Many
+parental modifications of structure and habit are
+certainly not conveyed to neuter ants and bees;
+other modifications, which are not seen in the
+parents, being conveyed instead. Many other
+circumstances tend to show that the individual
+and the transmissible type are independent of
+each other so far as modifications of parts are
+concerned.</p>
+
+<p>It may seem natural to expect the transmission
+of an enlarged muscle or a cultivated brain,
+but, on the other hand, why should it be unreasonable
+to expect that a modification which
+was non-congenital in origin should still remain
+non-congenital? Why should the non-transmission
+of that which was not transmitted be surprising?</p>
+
+<p>Mr. Spencer thinks that the non-transmission
+of acquired modifications is incongruous with the<span class='pagenum'><a name="Page_44" id="Page_44">[44]</a></span>
+great fact of atavism. But the great law of the
+inheritance of that which is a development of
+the transmissible type does not necessarily imply
+the inheritance of modifications acquired by the
+individual. Because English children may inherit
+blue eyes and flaxen hair from their Anglo-Saxon
+ancestors, it by no means follows that
+an Englishman must inherit his father's sunburnt
+complexion or smooth-shaven face. Of course
+atavism ultimately adopts many instances of
+revolt against its sway. But to assume that these
+changes of type <i>follow</i> the personal change rather
+than cause it, is to assume the whole question at
+issue. That like begets like is true as a broad
+principle, but it has many exceptions, and the
+non-heredity of acquired characters may be one
+of them.</p>
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote"><p><a name="Footnote_2_2" id="Footnote_2_2"></a><a href="#FNanchor_2_2"><span class="label">[2]</span></a> <i>Principles of Biology</i>, &sect; 166, footnote. The English jaws are
+somewhat lighter than the Australian jaws, though I could not
+undertake to affirm that they are really shorter and smaller. In
+the typical skulls depicted on p. 68 of the official guide to the
+mammalian galleries at South Kensington, the typical Caucasian
+jaw is very much larger than the Tasmanian jaw, although the
+repulsively obtrusive teeth of the latter convey the contrary idea to
+the imagination. Mr. Spencer's assumption that the ancient
+Britons had large jaws appears to me erroneous. (See Professor
+Rolleston's <i>Scientific Papers and Addresses</i>, i. p. 250.)</p></div>
+
+<div class="footnote"><p><a name="Footnote_3_3" id="Footnote_3_3"></a><a href="#FNanchor_3_3"><span class="label">[3]</span></a> Romanes, Galton, and Weismann have made great use of this
+principle in explaining the diminution of disused organs. Weismann
+has given it the name of <i>Panmixia</i>,&mdash;<i>all</i> individuals being
+equally free to survive and commingle their variations, and not
+merely selected or favoured individuals. See his <i>Essays on Heredity</i>,
+&amp;c., p. 90 (Clarendon Press).</p></div>
+
+<div class="footnote"><p><a name="Footnote_4_4" id="Footnote_4_4"></a><a href="#FNanchor_4_4"><span class="label">[4]</span></a> Inclusive in each case of fixed strengthening wire weighing
+about a sixteenth of an ounce or less.</p></div>
+
+<div class="footnote"><p><a name="Footnote_5_5" id="Footnote_5_5"></a><a href="#FNanchor_5_5"><span class="label">[5]</span></a> References of course are to <i>Factors of Organic Evolution</i>.</p></div>
+
+<div class="footnote"><p><a name="Footnote_6_6" id="Footnote_6_6"></a><a href="#FNanchor_6_6"><span class="label">[6]</span></a> P. 13; and <i>Nineteenth Century</i>, February, 1888, p. 211.</p></div>
+
+<div class="footnote"><p><a name="Footnote_7_7" id="Footnote_7_7"></a><a href="#FNanchor_7_7"><span class="label">[7]</span></a> Tomes's <i>Dental Surgery</i>, pp. 273-275. Tomes observes that
+it is as yet uncertain in what way civilization predisposes to caries.
+But he shows that caries is caused by the lime salts in the teeth
+being attacked by <i>acids</i> from decomposing food in crevices, from
+artificial drink such as cyder, from sugar, from medicine, and from
+vitiated secretions of the mouth. It is evident that in civilized
+races natural selection cannot so rigorously insist on sound teeth,
+sound constitutions, and <i>protective alkaline</i> saliva. The reaction of
+the civilized mouth is often acid, especially when the system is disordered
+by dyspepsia or other diseases or forms of ill-health common
+under civilization. The main supply of saliva, which is poured
+from the cheeks opposite the upper molars, is often acid when in
+small quantities. But the submaxillary and sub-lingual saliva
+poured out at the foot of the lower incisors and held in the front
+part of the jaw as in a spoon, "differs from parotid saliva in being
+more alkaline" (Foster's <i>Text Book of Physiology</i>, p. 238; Tomes,
+pp. 284, 685). One observer says that the reaction near the lower
+incisors is "never acid." Hence (I conclude) the remarkable immunity
+of the lower incisors and canines from decay, an immunity
+which extends backwards in a lessening degree to the first and
+second bicuspids. The close packing of the lower incisors may
+assist by preventing the retention of decaying fragments of food.
+Sexual selection may promote caries by favouring white teeth, which
+are more prone to decay than yellow ones. Acid vitiation of the
+mucus might account both for caries and (possibly) for the strange
+infertility of some inferior races under civilization.</p></div>
+
+<div class="footnote"><p><a name="Footnote_8_8" id="Footnote_8_8"></a><a href="#FNanchor_8_8"><span class="label">[8]</span></a> <i>Origin of Species</i>, pp. 198-9; <i>Variation of Animals and Plants
+under Domestication</i>, vol. ii. p. 328 footnote, also p. 206.</p></div>
+
+<div class="footnote"><p><a name="Footnote_9_9" id="Footnote_9_9"></a><a href="#FNanchor_9_9"><span class="label">[9]</span></a> Mr. Spencer weakly argues that an advantageous attribute
+(such as swiftness, keen sight, courage, sagacity, strength, &amp;c.)
+cannot be increased by natural selection unless it is "of greater importance,
+for the time being, than most of the other attributes";
+and that natural selection cannot develop any one superiority when
+animals are equally preserved by "other superiorities." But as
+natural selection will simultaneously eliminate tendencies to slowness,
+blindness, deafness, stupidity, &amp;c., it <i>must</i> favour and improve
+many points simultaneously, although no one of them may be of
+greater importance than the rest. Of course the more complicated
+the evolution the slower it will be; but time is plentiful, and
+the amount of elimination is correspondingly vast.</p></div>
+
+<div class="footnote"><p><a name="Footnote_10_10" id="Footnote_10_10"></a><a href="#FNanchor_10_10"><span class="label">[10]</span></a> I venture to coin this concise term to signify <i>the direct inheritance
+of the effects of use and disuse in kind</i>. Having a name for a
+thing is highly convenient; it facilitates clearness and accuracy in
+reasoning, and in this particular inquiry it may save some confusion
+of thought from double or incomplete meanings in the shortened
+phrases which would otherwise have to be employed to indicate this
+great but nameless factor of evolution.</p></div>
+
+<div class="footnote"><p><a name="Footnote_11_11" id="Footnote_11_11"></a><a href="#FNanchor_11_11"><span class="label">[11]</span></a> <i>Origin of Species</i>, pp. 230-232; Bates's <i>Naturalist on the
+Amazons</i>. Darwin is "surprised that no one has hitherto advanced
+the demonstrative case of neuter insects, against the well-known
+doctrine of inherited habit, as advanced by Lamarck." As he
+justly observes, "it proves that with animals, as with plants, any
+amount of modification may be effected by the accumulation of
+numerous, slight, spontaneous variations, which are in any way
+profitable, without exercise or habit having been brought into play.
+For peculiar habits confined to the workers or sterile females, however
+long they might be followed, could not possibly affect the
+males and fertile females, which alone leave any descendants."
+Some slight modification of these remarks, however, may possibly
+be needed to meet the case of "factitious queens," who (probably
+through eating particles of the royal food) become capable of producing
+a few male eggs.</p></div>
+
+<div class="footnote"><p><a name="Footnote_12_12" id="Footnote_12_12"></a><a href="#FNanchor_12_12"><span class="label">[12]</span></a> <i>Descent of Man</i>, pp. 573, 572, and footnote.</p></div>
+
+<div class="footnote"><p><a name="Footnote_13_13" id="Footnote_13_13"></a><a href="#FNanchor_13_13"><span class="label">[13]</span></a> <i>Contemporary Review</i>, December, 1875, p. 92.</p></div>
+
+<div class="footnote"><p><a name="Footnote_14_14" id="Footnote_14_14"></a><a href="#FNanchor_14_14"><span class="label">[14]</span></a> See <i>Origin of Species</i>, pp. 5-8. "Changed conditions induce
+an almost indefinite amount of fluctuating variability, by which the
+whole organization is rendered in some degree plastic" (<i>Descent of
+Man</i>, p. 30). It also appears that "the nature of the conditions is
+of subordinate importance in comparison with the nature of the organism
+in determining each particular form of variation;&mdash;perhaps
+of not more importance than the nature of the spark, by which a
+mass of combustible matter is ignited, has in determining the nature
+of the flames" (<i>Origin of Species</i>, p. 8).</p></div>
+</div>
+
+<hr /><p><span class='pagenum'><a name="Page_45" id="Page_45">[45]</a></span></p>
+<h2>DARWIN'S EXAMPLES.</h2>
+
+<p class="noin"><span class="smcap">The</span> most formidable cases brought forward by
+Mr. Spencer are from Darwin. I shall endeavour
+to show, however, that Darwin was probably wrong
+in retaining the older explanation of these facts,
+and that the remains of the Lamarckian theory of
+use-inheritance need not any longer encumber
+the great explanation which has superseded that
+fallacious and unproven theory and has rendered
+it totally unnecessary. Meanwhile I think it is an
+excellent sign that Mr. Spencer has to complain
+that "Nowadays most naturalists are more Darwinian
+than Mr. Darwin himself"&mdash;inasmuch as
+they are inclined to say that there is "no proof"
+that the effects of use and disuse are inherited.<span class='pagenum'><a name="Page_46" id="Page_46">[46]</a></span>
+Other excellent signs are the recent issue of a translation
+of Weismann's important essays on this and
+kindred subjects,<a name="FNanchor_15_15" id="FNanchor_15_15"></a><a href="#Footnote_15_15" class="fnanchor">[15]</a> the strong support given to his
+views by Wallace in his <i>Darwinism</i>, and their
+adoption by Ray Lankester in his article on
+Zoology in the latest edition of the <i>Encyclop&aelig;dia
+Britannica</i>. So sound and cautious an investigator
+as Francis Galton had also in 1875 concluded
+that "acquired modifications are barely, if at all,
+<i>inherited</i>, in the correct sense of that word."</p>
+
+<p>Darwin's belief in the inheritance of acquired
+characters was more or less hereditary in the
+family. His grandfather, Erasmus Darwin, anticipated
+Lamarck's views in his <i>Zoonomia</i>,
+which Darwin at one time "greatly admired."
+His father was "convinced" of the "inherited evil
+effects of alcohol," and to this extent at least he
+strongly impressed the belief in the inheritance<span class='pagenum'><a name="Page_47" id="Page_47">[47]</a></span>
+of acquired characters upon his children's minds.<a name="FNanchor_16_16" id="FNanchor_16_16"></a><a href="#Footnote_16_16" class="fnanchor">[16]</a>
+Darwin must also have been imbued with Lamarckian
+ideas from other sources, although
+Dr. Grant's enthusiastic advocacy entirely failed
+to convert him to a belief in evolution.<a name="FNanchor_17_17" id="FNanchor_17_17"></a><a href="#Footnote_17_17" class="fnanchor">[17]</a> "Nevertheless,"
+he says, "it is probable that the hearing
+rather early in life such views maintained and
+praised may have favoured my upholding them
+under a different form in my <i>Origin of Species</i>"&mdash;a
+remark which refers to Lamarck's views on the
+general doctrine of evolution, but might also prove
+equally true if applied to Darwin's partial retention
+of the Lamarckian explanation of that evolution.
+Professor Huxley has pointed out that in<span class='pagenum'><a name="Page_48" id="Page_48">[48]</a></span>
+Darwin's earlier sketch of his theory of evolution
+(1844) he attached more weight to the inheritance
+of acquired habits than he does in his
+<i>Origin of Species</i> published fifteen years later.<a name="FNanchor_18_18" id="FNanchor_18_18"></a><a href="#Footnote_18_18" class="fnanchor">[18]</a>
+He appears to have acquired the belief in early
+life without first questioning and rigorously testing
+it as he would have done had it originated
+with himself. In later life it appeared to assist his
+theory of evolution in minor points, and in
+particular it appeared absolutely indispensable
+to him as the <i>only</i> explanation of the diminution
+of disused parts in cases where, as in domestic
+animals, economy of growth seemed to be practically
+powerless. He failed to adequately notice
+the effect of panmixia, or the withdrawal of
+selection, in causing or allowing degeneracy and
+dwindling under disuse; and he hardly attached
+sufficient importance to the fact that rudimentary
+organs and other supposed effects of use or<span class='pagenum'><a name="Page_49" id="Page_49">[49]</a></span>
+disuse are quite as marked features in neuter
+insects which cannot transmit the effects of use
+and disuse as they are in the higher animals.</p>
+
+<h3>REDUCED WINGS OF BIRDS OF OCEANIC ISLANDS.</h3>
+
+<p>Darwin himself has pointed out that the rudimentary
+wings of island beetles, at first thought
+to be due to disuse, are mainly brought about by
+natural selection&mdash;the best-winged beetles being
+most liable to be blown out to sea. But he says
+that in birds of the oceanic islands "not persecuted
+by any enemies, the reduction of their
+wings has probably been caused by disuse." This
+explanation may be as fallacious as it is acknowledged
+to have been in the case of the island
+beetles. According to Darwin's own views,
+natural selection <i>must</i> at least have played an
+important part in reducing the wings; for he<span class='pagenum'><a name="Page_50" id="Page_50">[50]</a></span>
+holds that "natural selection is continually trying
+to economize every part of the organization."
+He says: "If under changed conditions of life
+a structure, before useful, becomes less useful, its
+diminution will be favoured, for it will profit the
+individual not to have its nutriment wasted in
+building up an useless structure.... Thus, as I
+believe, natural selection will tend in the long
+run to reduce any part of the organization, as
+soon as it becomes, through changed habits,
+superfluous."<a name="FNanchor_19_19" id="FNanchor_19_19"></a><a href="#Footnote_19_19" class="fnanchor">[19]</a> If, as Darwin powerfully urges
+(and he here ignores his usual explanation),
+ostriches' wings are insufficient for flight in consequence
+of the economy enforced by natural
+selection,<a name="FNanchor_20_20" id="FNanchor_20_20"></a><a href="#Footnote_20_20" class="fnanchor">[20]</a> why may not the reduced wings
+of the dodo, or the penguin, or the apteryx, or of
+the Cursores generally, be wholly attributed to
+natural selection in favour of economy of material
+and adaptation of parts to changed conditions?<span class='pagenum'><a name="Page_51" id="Page_51">[51]</a></span>
+The great principle of economy is continually at
+work shaping organisms, as sculptors shape statues,
+by removing the superfluous parts; and a mere
+glance at the forms of animals in general will
+show that it is well-nigh as dominant and universal
+a principle as is that of the positive
+development of useful parts. Other causes, moreover
+besides actual economy, would favour shorter
+and more convenient wings on oceanic islands.
+In the first place, birds that were somewhat weak
+on the wing would be most likely to settle on an
+island and stay there. Shortened wings would
+then become advantageous because they would
+restrain fatal migratory tendencies or useless
+and perilous flights in which the birds that flew
+furthest would be most often carried away by
+storms and adverse winds. Reduced wings would
+keep the birds near the shelter and the food
+afforded by the island and its neighbourhood,
+and in some cases would become adapted to act<span class='pagenum'><a name="Page_52" id="Page_52">[52]</a></span>
+as fins or flappers for swimming under water in
+pursuit of fish.</p>
+
+<p>The reduced size of the wings of these island
+birds is paralleled by the remarkable thinness,
+&amp;c., of the shell of the "gigantic land-tortoise"
+of the Galapagos Islands. The changes seen in
+the carapace can hardly have been brought about
+by the inherited effects of special disuse. Why
+then should not the reduction of equally useless,
+more wasteful, and perhaps positively dangerous
+wings be also due to an economy which has become
+advantageous to bird and reptile alike through
+the absence of the mammalian rivals whose places
+they are evidently being modified to fill? The
+<i>complete</i> loss of the wings in neuter ants and termites
+can scarcely be due to the inherited effects
+of disuse; and as natural selection has abolished
+these wings in spite of the opposition of use-inheritance,
+it must clearly be fully competent to
+reduce wings without its aid. In considering the<span class='pagenum'><a name="Page_53" id="Page_53">[53]</a></span>
+rudimentary wings of the apteryx, or of the moa,
+emu, ostrich, &amp;c., we must not forget the frequent
+or occasional occurrence of hard seasons, and times
+of drought and famine, when Nature eliminates
+redundant, wasteful, and ill-adapted organisms in
+so severe and wholesale a fashion. Where enemies
+are absent there would be unrestrained multiplication,
+and this would greatly increase the severity
+of the competition for food, and so hasten the
+elimination of disused and useless parts.</p>
+
+<h3>DROOPING EARS AND DETERIORATED
+INSTINCTS.</h3>
+
+<p>Mr. Galton has pointed out that existing races
+and existing organs are only kept at their present
+high pitch of organic excellence by the stringent
+and incessant action of natural or artificial
+selection; and the simple relaxation or withdrawal
+of such selective influences will almost necessarily<span class='pagenum'><a name="Page_54" id="Page_54">[54]</a></span>
+result in a certain amount of deterioration, independently
+even of the principle of economy.<a name="FNanchor_21_21" id="FNanchor_21_21"></a><a href="#Footnote_21_21" class="fnanchor">[21]</a> I
+think that this cessation of a previous selective
+process will account for the drooping&mdash;but <i>not
+diminished</i>&mdash;ears of various domesticated animals
+(human preference and increased weight evidently
+aiding), and also for the inferior instincts seen in
+them and in artificially-fed caterpillars of the silk-moth,
+which now "often commit the strange mistake
+of devouring the base of the leaf on which
+they are feeding, and consequently fall down."
+Anyhow, I fail to see that anything is proved by
+this latter case, except that natural instinct may
+be perverted or aborted under unnatural conditions
+and a changed method of selection which
+abolishes the powerful corrective formerly supplied
+by natural selection.</p>
+
+<p><span class='pagenum'><a name="Page_55" id="Page_55">[55]</a></span></p>
+<h3>WINGS AND LEGS OF DUCKS AND FOWLS.</h3>
+
+<p>The reduced wings and enlarged legs of domesticated
+ducks and fowls are attributed by Darwin and
+Spencer to the inheritance of the effects of use and
+disuse. But the inference by no means follows.
+Natural selection would usually favour these adaptive
+changes, and they would also have been aided
+by an artificial selection which is often unconscious
+or indirect. Birds with diminished power of flight
+would be less difficult to keep and manage, and
+in preserving and multiplying such birds man would
+be unconsciously bringing about structural changes
+which would easily be regarded as effects of
+use and disuse. "About eighteen centuries ago
+Columella and Varro speak of the necessity
+of keeping ducks in netted enclosures like other
+wild fowl, so that at this period there was danger
+of their flying away."<a name="FNanchor_22_22" id="FNanchor_22_22"></a><a href="#Footnote_22_22" class="fnanchor">[22]</a> Is it not probable that the<span class='pagenum'><a name="Page_56" id="Page_56">[56]</a></span>
+best fliers would escape most frequently, or would
+pine most if kept confined? On the other hand,
+birds with lessened powers of flight would not be
+eliminated as under natural conditions, but would
+be favoured; and natural selection, together with
+artificial selection of the most flourishing birds,
+would thicken and strengthen the legs to meet
+increased demands upon them.</p>
+
+<p>The diminution of the duck's wing is not great
+even in the birds that "never fly," and from
+this we must deduct the direct effect of disuse on
+the individual during its lifetime. As Weismann
+suggests, the <i>inherited</i> portion of the change could
+only be ascertained by comparing the bones, &amp;c.,
+of wild and tame ducks <i>similarly reared</i>. If
+individual disuse diminished the weight of the
+duck's wing-bones by 9 per cent. there would
+be nothing left to account for.</p>
+
+<p>I suspect that investigation would reveal anomalies
+inconsistent with the theory of use-inheritance.<span class='pagenum'><a name="Page_57" id="Page_57">[57]</a></span>
+Thus according to Darwin's tables
+of comparative weights and measurements<a name="FNanchor_23_23" id="FNanchor_23_23"></a><a href="#Footnote_23_23" class="fnanchor">[23]</a> the
+leg-bones of the Penguin duck have slightly
+diminished in length, although they have increased
+39 per cent. in weight. Relatively to
+the weight of the skeleton, the leg-bones have
+shortened in the tame breeds of ducks by over
+5 per cent. (and in two breeds by over 8 per cent.)
+although they have increased more than 28 per
+cent. in proportional weight.<a name="FNanchor_24_24" id="FNanchor_24_24"></a><a href="#Footnote_24_24" class="fnanchor">[24]</a> How can increased
+use simultaneously shorten and thicken these bones?
+If the relative shortening is attributed to a heavier<span class='pagenum'><a name="Page_58" id="Page_58">[58]</a></span>
+skeleton, then the apparently reduced weight of
+the wing-bones is fully accounted for by the same
+circumstance, and disuse has had no inherited
+effect.</p>
+
+<p>Another strange circumstance is that the wing-bones
+have diminished <i>in length only</i>. The shortening
+is about 6 per cent. more than in the shortened
+legs, and it amounts to 11 per cent. as compared
+with the weight of the skeleton. Such a shortening
+should represent a reduction of 29 per cent. in
+weight, whereas the actual reduction in the weight
+of the wing-bones relatively to the weight of the
+skeleton is only 9 per cent. even in the breeds
+that never fly. Independently of shortening, the
+disused wing-bones have actually thickened or
+increased in weight. In the Aylesbury duck
+the disproportion caused by these conflicting
+changes is so great that the wing-bones are
+47 per cent. heavier than they should be if
+their weight had varied proportionally with their<span class='pagenum'><a name="Page_59" id="Page_59">[59]</a></span>
+length.<a name="FNanchor_25_25" id="FNanchor_25_25"></a><a href="#Footnote_25_25" class="fnanchor">[25]</a> The reduction in weight on which Darwin
+relies seems to be entirely due to the shortening,
+and this shortening appears to be irrelevant to
+disuse, since the wings of the Call duck are similarly
+shortened in their proportions by 12 per cent.,
+although this bird habitually flies to such an
+extent that Darwin partly attributes the greatly
+increased weight of its wing-bones to increased use
+under domestication.</p>
+
+<p>We find that <i>all</i> the changes are in the
+direction of shorter and thicker bones&mdash;a tendency
+which must be largely dependent upon the suspension
+of the rigorous elimination which keeps the<span class='pagenum'><a name="Page_60" id="Page_60">[60]</a></span>
+bones of the wild duck <i>long and light</i>. The
+used leg-bones and the disused wing-bones have
+alike been shortened and thickened, though in
+different proportions. Natural or artificial selection
+might easily thicken legs without lengthening
+them, or shorten wings without eliminating strong
+heavy bones, but it can hardly be contended that
+use-inheritance has acted in such conflicting ways.
+The thickening of the wing-bones has actually
+more than kept pace with any increase of weight
+in the skeleton, in spite of the effect of individual
+disuse and of the alleged cumulative effect
+of ancestral disuse for hundreds of generations.
+The case of the duck deserves special attention
+as a crucial one, if only from the fact that in
+this instance, and in this instance only, has Darwin
+given the weights of the skeletons, thus furnishing
+the means for a closer examination of his details
+than is usually possible.</p>
+
+<p>If we ignore such factors as selection, panmixia,<span class='pagenum'><a name="Page_61" id="Page_61">[61]</a></span>
+correlation, and the effects of use and
+disuse during lifetime, and still regard the case
+of the domestic duck as a valid proof of the
+inheritance of the effects of use and disuse, we
+must also accept it as an equally valid proof that
+the effects of use and disuse are <i>not</i> inherited.
+Nay, we may even have to admit that, in two
+points out of four, the <i>inherited</i> effect of use and
+disuse on successive generations is exactly opposite
+to the immediate effect on the individual.</p>
+
+<p>Among fowls the wing-bones have lost much
+in weight but little or nothing in length&mdash;which is
+the reverse of what has occurred in ducks, although
+disuse is alleged to be the common cause in both
+cases. Some of the fowls which fly least have
+their wing-bones as long as ever. In the case of
+the Silk and Frizzled fowls&mdash;ancient breeds which
+"cannot fly at all"&mdash;and in that of the Cochins,
+which "can hardly fly up to a low perch," Darwin
+observes "how truly the proportions of an organ<span class='pagenum'><a name="Page_62" id="Page_62">[62]</a></span>
+may be inherited although not fully exercised
+during many generations."<a name="FNanchor_26_26" id="FNanchor_26_26"></a><a href="#Footnote_26_26" class="fnanchor">[26]</a> In four out of twelve
+breeds the wing-bones had become slightly heavier
+relatively to the leg-bones. Do not these facts
+tend to show that the changes in fowls' wings
+are due to fluctuating variability and selective
+influences rather than to a general law whereby the
+effects of disuse are cumulatively inherited?</p>
+
+<h3>PIGEONS' WINGS.</h3>
+
+<p>Concerning pigeons' wings Darwin says: "As
+fancy pigeons are generally confined in aviaries
+of moderate size, and as even when not confined
+they do not search for their own food, they must
+during many generations have used their wings
+incomparably less than the wild rock-pigeon ... but
+when we turn to the wings we find what at<span class='pagenum'><a name="Page_63" id="Page_63">[63]</a></span>
+first appears a wholly different and unexpected
+result."<a name="FNanchor_27_27" id="FNanchor_27_27"></a><a href="#Footnote_27_27" class="fnanchor">[27]</a> This unexpected increase in the spread of
+the wings from tip to tip is due to the feathers,
+which have lengthened in spite of disuse. Excluding
+the feathers, the wings were shorter in seventeen
+instances, and longer in eight. But as artificial
+selection has lengthened the wings in some
+instances, why may it not have shortened
+them in others? Wings with shortened bones
+would fold up more neatly than the long wings
+of the Carrier pigeon for instance, and so might
+unconsciously be favoured by fanciers. The
+selection of elegant birds with longer necks or
+bodies would cause a relative reduction in the
+wings&mdash;as with the Pouter, where the wings
+have been greatly lengthened but not so
+much as the body.<a name="FNanchor_28_28" id="FNanchor_28_28"></a><a href="#Footnote_28_28" class="fnanchor">[28]</a> Slender bodies, too, and the
+lessened divergence of the furculum,<a name="FNanchor_29_29" id="FNanchor_29_29"></a><a href="#Footnote_29_29" class="fnanchor">[29]</a> would<span class='pagenum'><a name="Page_64" id="Page_64">[64]</a></span>
+slightly diminish the spread of the wings, and so
+would affect the measurements taken. As the
+wing-bones, moreover, are to some extent correlated
+with the beak and the feet, the artificial
+selection of shortened beaks might tend to shorten
+the wing as well as the feet. Under these
+circumstances how can we be sure of the actual
+efficacy of use-inheritance? Surely selection is as
+fully competent to effect slight changes in the
+direction of use-inheritance as it undoubtedly is
+to effect great changes in direct opposition to that
+alleged factor of evolution.</p>
+
+<h3>SHORTENED BREAST-BONE IN PIGEONS.</h3>
+
+<p>The shortening of the sternum in pigeons is attributed
+to disuse of the flight muscles attached to
+it. The bone is only shortened by a third of an
+inch, but this represents a very remarkable reduction
+in proportional length, which Darwin estimates at<span class='pagenum'><a name="Page_65" id="Page_65">[65]</a></span>
+from one-seventh to one-eighth, or over 13 per
+cent. This marked reduction, too, quite unlike
+the slight reduction of the wing-bones to which
+the other ends of the muscles are attached, was
+universal in the eleven specimens measured by
+Darwin; and the bone, though acknowledged
+to have been modified by artificial selection
+in some breeds, is not so open to observation as
+wings or legs. Even, however, if this relative
+shortening of the sternum remained otherwise
+inexplicable, it might still be as irrelevant to use
+and disuse as is the fact that "many breeds"
+of fancy pigeons have lost a rib, having only
+seven where the ancestral rock-pigeon has eight.<a name="FNanchor_30_30" id="FNanchor_30_30"></a><a href="#Footnote_30_30" class="fnanchor">[30]</a>
+But the excessive reduction in the sternum is
+far from being inexplicable. In the first place
+Darwin has somewhat over-estimated it. Instead
+of comparing the deficiency of length with the
+increased length which <i>should</i> have been acquired<span class='pagenum'><a name="Page_66" id="Page_66">[66]</a></span>
+(since the pigeons have increased in average size)
+he compares it with the length of the breast-bone
+in the rock-pigeon.<a name="FNanchor_31_31" id="FNanchor_31_31"></a><a href="#Footnote_31_31" class="fnanchor">[31]</a> By this method if a
+pigeon had doubled in dimensions while its
+breast-bone remained unaltered, the reduction
+would be put down as 100 per cent., whereas
+obviously the true reduction would be one-half,
+or 50 per cent. of what the bone <i>should be</i>.
+Avoiding this error and a minor fallacy besides,
+a sound estimate reduces the supposed reduction
+of 13 or 14 per cent. to one of 11&middot;7 per cent., which
+is still of course a considerable diminution.</p>
+
+<p>Part of this reduction must be due to the direct
+effect of disuse during the lifetime of the individual.
+Another and perhaps very considerable
+part of the relative change must be attributed
+to the lengthening of the neck or body by<span class='pagenum'><a name="Page_67" id="Page_67">[67]</a></span>
+artificial selection, or to other modifications of
+shape and proportion effected directly or indirectly
+by the same cause.<a name="FNanchor_32_32" id="FNanchor_32_32"></a><a href="#Footnote_32_32" class="fnanchor">[32]</a> The reduction is greatest in
+the Pouter (18&frac12; per cent.) and in the Pied Scanderoon
+(17&frac12; per cent.). In the former the body has
+been greatly elongated by artificial selection and
+three or four additional vertebr&aelig; have been acquired
+in the hinder part of the body.<a name="FNanchor_33_33" id="FNanchor_33_33"></a><a href="#Footnote_33_33" class="fnanchor">[33]</a> In the latter a
+long neck increases the length of the bird, and so
+causes, or helps to cause, the relative shortening of
+the breast-bone. In the English Carrier&mdash;which
+experiences the effects of disuse, as it is too
+valuable to be flown&mdash;the relative reduction of
+11 per cent. is apparently more than accounted<span class='pagenum'><a name="Page_68" id="Page_68">[68]</a></span>
+for by the "elongated neck." The Dragon also
+has a long neck. In the Pouter, although the
+breast-bone has been shortened by 18&frac12; per
+cent. relatively to the length of the body, it
+has <i>lengthened</i> by 20 per cent. relatively to
+the <i>bulk</i> of the body.<a name="FNanchor_34_34" id="FNanchor_34_34"></a><a href="#Footnote_34_34" class="fnanchor">[34]</a> Darwin forgot to ask
+whether allowance must not be made for a
+frequent, or perhaps general, elongation of the
+neck and the hinder part of the body, and the
+relative shortening or the throwing forward of the
+central portion containing the ribs (frequently
+one less in number) and the sternum. The whole
+body of the pigeon is so much under the control
+of artificial selection, that every precaution must
+be taken to guard against such possible sources of
+error.<a name="FNanchor_35_35" id="FNanchor_35_35"></a><a href="#Footnote_35_35" class="fnanchor">[35]</a></p>
+
+<p><span class='pagenum'><a name="Page_69" id="Page_69">[69]</a></span></p><p>Under domestication there would be a suspension
+of the previous elimination of reduced breast-bones
+by natural selection (Weismann's panmixia),
+and a diminution of the parts concerned in flying
+might even be favoured, as lessened powers of
+<i>continuous</i> flight would prevent pigeons from straying
+too far, and would fit them for domestication
+or confinement. Such causes might reduce some of
+the less observed parts affected by flying, while
+still leaving the wing of full size for occasional
+flight, or to suit the requirements of the pigeon-fanciers.
+A change might thus be commenced
+like that seen in the rudimentary keel of the
+sternum in the owl-parrot of New Zealand,
+which has lost the power of flight although
+still retaining fairly-developed wings.</p>
+
+<p><span class='pagenum'><a name="Page_70" id="Page_70">[70]</a></span></p>
+<h3>SHORTENED FEET IN PIGEONS.</h3>
+
+<p>Darwin thinks it highly probable that the short
+feet of most breeds of pigeons are due to lessened
+use, though he owns that the effects of correlation
+with the shortened beak are more plainly shown
+than the effects of disuse.<a name="FNanchor_36_36" id="FNanchor_36_36"></a><a href="#Footnote_36_36" class="fnanchor">[36]</a> But why need the
+inherited effects of disuse be called in to explain
+an average reduction of some 5 per cent., when
+Darwin's measurements show that in the breeds
+where long beaks are favoured the principle of
+correlation between these parts has lengthened
+the foot by 13 per cent. in spite of disuse?</p>
+
+<h3>SHORTENED LEGS OF RABBITS.</h3>
+
+<p>In the case of the domestic rabbit Darwin
+notices that the bones of the legs have (relatively)
+become shorter by an inch and a half. But<span class='pagenum'><a name="Page_71" id="Page_71">[71]</a></span>
+as the leg-bones have <i>not</i> diminished in relative
+weight,<a name="FNanchor_37_37" id="FNanchor_37_37"></a><a href="#Footnote_37_37" class="fnanchor">[37]</a> they must clearly have grown <i>thicker</i>
+or denser. If disuse has shortened them, as
+Darwin supposes, why has it also thickened them?
+The ears and the tail have been lengthened in
+spite of disuse. Why then may not the ungainly
+hind-legs have been shortened by human preference
+independently of the inherited effects of
+disuse? By relying on apparently favourable
+instances and neglecting the others it would be
+easy to arrive at all manner of unsound conclusions.
+We might thus become convinced that vessels
+tend to sail northwards, or that a pendulum
+oscillates more often in one direction than in
+the other. It must not be forgotten that it
+would be easy to cite an enormous number of
+cases which are in direct conflict with the
+supposed law of use-inheritance.</p>
+
+<p><span class='pagenum'><a name="Page_72" id="Page_72">[72]</a></span></p>
+<h3>BLIND CAVE-ANIMALS.</h3>
+
+<p>Weak or defective eyesight is by no means
+rare as a spontaneous variation in animals,
+"the great French veterinary Huzard going
+so far as to say that a blind race [of horses]
+could soon be formed." Natural selection evolves
+blind races whenever eyes are useless or
+disadvantageous, as with parasites. This may
+apparently be done independently of the effects
+of disuse, for certain neuter ants have eyes which
+are reduced to a more or less rudimentary
+condition, and neuter termites are blind as well
+as wingless. In one species of ant (<i>Eciton vastator</i>)
+the sockets have disappeared as well as the eyes.
+In deep caves not only would natural selection
+cease to maintain good eyesight but it would
+persistently favour blindness&mdash;or the entire
+removal of the eye when greatly exposed, as in
+the cave-crab&mdash;and as Dr. Ray Lankester has<span class='pagenum'><a name="Page_73" id="Page_73">[73]</a></span>
+indicated,<a name="FNanchor_38_38" id="FNanchor_38_38"></a><a href="#Footnote_38_38" class="fnanchor">[38]</a> there would have been a previous
+selection of animals which through spontaneous
+weakness, sensitiveness, or other affection of the
+eye found refuge and preservation in the cave,
+and a subsequent selection of the descendants
+whose fitness for relative darkness led them
+deeper into the cave or prevented them from
+straying back to the light with its various
+dangers and severer competition. Panmixia,
+however, as Weismann has shown, would probably
+be the most important factor in causing blindness.</p>
+
+<h3>INHERITED HABITS.</h3>
+
+<p>Darwin says: "A horse is trained to certain
+paces, and the colt inherits similar consensual
+movements."<a name="FNanchor_39_39" id="FNanchor_39_39"></a><a href="#Footnote_39_39" class="fnanchor">[39]</a> But selection of the constitutional<span class='pagenum'><a name="Page_74" id="Page_74">[74]</a></span>
+tendency to these paces, and imitation of the mother
+by the colt, may have been the real causes. The
+evidence, to be satisfactory, should show that
+such influences were excluded. Men acquire
+proficiency in swimming, waltzing, walking, smoking,
+languages, handicrafts, religious beliefs, &amp;c.,
+but the children only appear to inherit the innate
+abilities or constitutional proclivities of their
+parents. Even the songs of birds, including
+their call-notes, are no more inherited than is
+language by man (<i>Descent of Man</i>, p. 86). They
+are learned from the parent. Nestlings which
+acquire the song of a distinct species, "teach
+and transmit their new song to their offspring."
+If use-inheritance has not fixed the song of birds,
+why should we suppose that in a single
+generation it has transmitted a newly-taught
+method of walking or trotting?</p>
+
+<p>It is alleged that dogs inherit the intelligence
+acquired by association with man,<span class='pagenum'><a name="Page_75" id="Page_75">[75]</a></span>
+and that retrievers inherit the effects of their
+training.<a name="FNanchor_40_40" id="FNanchor_40_40"></a><a href="#Footnote_40_40" class="fnanchor">[40]</a> But selection and imitation are so
+potent that the additional hypothesis of use-inheritance
+seems perfectly superfluous. Where
+intelligence is not highly valued and carefully
+promoted by selection, the intelligence derivable
+from association with man does <i>not</i> appear
+to be inherited. Lap-dogs, for instance, are often
+remarkably stupid.</p>
+
+<p>Darwin also instances the inheritance of dexterity
+in seal-catching as a case of use-inheritance.<a name="FNanchor_41_41" id="FNanchor_41_41"></a><a href="#Footnote_41_41" class="fnanchor">[41]</a>
+But this is amply explained by the ordinary
+law of heredity. All that is needed is that the
+son shall inherit the suitable faculties which the
+father inherited before him.</p>
+
+<p><span class='pagenum'><a name="Page_76" id="Page_76">[76]</a></span></p>
+<h3>TAMENESS OF RABBITS.</h3>
+
+<p>Darwin holds that in some cases selection alone
+has modified the instincts and dispositions of
+domesticated animals, but that in most cases
+selection and the inheritance of acquired habits
+have concurred in effecting the change. "On the
+other hand," he says, "habit alone in some cases
+has sufficed; hardly any animal is more difficult
+to tame than the young of the wild rabbit;
+scarcely any animal is tamer than the young of
+the tame rabbit; but I can hardly suppose that
+domestic rabbits have often been selected for
+tameness alone; so that we must attribute at least
+the greater part of the inherited change from
+extreme wildness to extreme tameness to habit
+and long-continued close confinement."<a name="FNanchor_42_42" id="FNanchor_42_42"></a><a href="#Footnote_42_42" class="fnanchor">[42]</a></p>
+
+<p>But there are strong, and to me irresistible,
+arguments to the contrary. I think that the following<span class='pagenum'><a name="Page_77" id="Page_77">[77]</a></span>
+considerations will show that the greater
+part, if not the whole, of the change must be
+attributed to selection rather than to the direct
+inheritance of acquired habit.</p>
+
+<p>(1) For a period which may cover thousands of
+generations, there has been an entire cessation of
+the natural selection which maintains the wildness
+(or excessive fear, caution, activity, &amp;c.) so indispensably
+essential for preserving defenceless wild
+rabbits of all ages from the many enemies that
+prey upon them.</p>
+
+<p>(2) During this same extensive period of time
+man has usually killed off the wildest and bred
+from the tamest and most manageable. To some
+extent he has done this consciously. "It is very
+conducive to successful breeding to keep only such
+as are quiet and tractable," says an authority on
+rabbits,<a name="FNanchor_43_43" id="FNanchor_43_43"></a><a href="#Footnote_43_43" class="fnanchor">[43]</a> and he enjoins the selection of the<span class='pagenum'><a name="Page_78" id="Page_78">[78]</a></span>
+handsomest and <i>best-tempered</i> does to serve as
+breeders. To a still greater extent man has
+favoured tameness unconsciously and indirectly.
+He has systematically selected the largest and
+most prolific animals, and has thus doubled the
+size and the fertility of the domestic rabbit. In
+consciously selecting the largest and most flourishing
+individuals and the best and most prolific
+mothers, he <i>must</i> have unconsciously selected
+those rabbits whose relative <i>tameness</i> or placidity
+of disposition rendered it possible for them to
+flourish and to produce and rear large and thriving
+families, instead of fretting and pining as the
+wilder captives would do. When we consider
+how exceedingly delicate and easily disturbed yet
+all-important a function is that of maternity in
+the continually breeding rabbit, we see that the
+tamest and the least terrified would be the most
+successful mothers, and so would continually be
+selected, although man cared nothing for the tameness<span class='pagenum'><a name="Page_79" id="Page_79">[79]</a></span>
+in itself. The tamest mothers would also
+be less liable to neglect or devour their offspring,
+as rabbits commonly do when their young are
+handled too soon, or even when merely frightened
+by mice, &amp;c., or disturbed by changed surroundings.</p>
+
+<p>(3) We must remember the extraordinary fecundity
+of the rabbit and the excessive amount of
+elimination that consequently takes place either
+naturally or artificially. Where nature preserved
+only the wildest, man has preserved the tamest.
+If there is any truth in the Darwinian theory, this
+thorough and long-continued reversal of the selective
+process <i>must</i> have had a powerful effect.
+Why should it not be amply sufficient to account
+for the tameness and mental degeneracy of the
+rabbit without the aid of a factor which can readily
+be shown to be far weaker in its normal action
+than either natural or artificial selection? Why
+may not the tameness of the rabbit be transferred<span class='pagenum'><a name="Page_80" id="Page_80">[80]</a></span>
+to the group of cases in which Darwin holds that
+"habit has done nothing," and selection has done
+all?</p>
+
+<p>(4) If use-inheritance has tamed the rabbit, why
+are the bucks still so mischievous and unruly?
+Why is the Angora breed the only one in which
+the males show no desire to destroy the young?
+Why, too, should use-inheritance be so much more
+powerful in the rabbit than with other animals
+which are far more easily tamed in the first instance?
+Wild young rabbits when domesticated
+"remain unconquerably wild," and, although they
+may be kept alive, they pine and "rarely come to
+any good." Yet the animal which <i>acquires</i> least
+tameness&mdash;or apparently, indeed, none at all&mdash;inherits
+most! It appears, in fact, to inherit that
+which it cannot acquire&mdash;a circumstance which
+indicates the selection of spontaneous variations
+rather than the inheritance of changed habits.
+Such variations occasionally occur in animals in a<span class='pagenum'><a name="Page_81" id="Page_81">[81]</a></span>
+marked degree. Of a litter of wolf-cubs, all
+brought up in the same way, "one became tame
+and gentle like a dog, while the others preserved
+their natural savagery." Is it not probable that
+permanent domestication was rendered possible by
+the inevitable selection of spontaneous variations in
+this direction? The <i>excessive</i> tameness, too, of the
+young rabbit, while easily explicable as a result of
+unconscious selection, is not easily explained as a
+result of acquired habit. No particular care is
+taken to tame or teach or domesticate rabbits.
+They are bred for food, or for profit or appearance,
+and they are left to themselves most of their
+time. As Sir J. Sebright notices with some surprise,
+the domestic rabbit "is not often visited,
+and seldom handled, and yet it is always tame."</p>
+
+<p><span class='pagenum'><a name="Page_82" id="Page_82">[82]</a></span></p>
+<h3>MODIFICATIONS OBVIOUSLY ATTRIBUTABLE TO
+SELECTION.</h3>
+
+<p>Innumerable modifications in accordance with
+altered use or disuse, such as the enlarged udders
+of cows and goats, and the diminished lungs and
+livers in highly bred animals that take little exercise,
+can be readily and fully explained as depending
+on selection. As the fittest for the natural
+or artificial requirements will be favoured, natural
+or artificial selection may easily enlarge organs
+that are increasingly used and economize in those
+that are less needed. I therefore see no necessity
+whatever for calling in the aid of use-inheritance
+as Darwin does, to account for enlarged udders, or
+diminished lungs, or the thick arms and thin legs
+of canoe Indians, or the enlarged chests of mountaineers,
+or the diminished eyes of moles, or the
+lost feet of certain beetles, or the reduced wings of
+logger-headed ducks, or the prehensile tails of<span class='pagenum'><a name="Page_83" id="Page_83">[83]</a></span>
+monkeys, or the displaced eyes of soles, or the
+altered number of teeth in plaice, or the increased
+fertility of domesticated animals, or the shortened
+legs and snouts of pigs, or the shortened intestines
+of tame rabbits, or the lengthened intestines of
+domestic cats, &amp;c.<a name="FNanchor_44_44" id="FNanchor_44_44"></a><a href="#Footnote_44_44" class="fnanchor">[44]</a> Changed habits and the requisite
+change of structure will usually be favoured
+by natural selection; for habit, as Darwin says,
+"almost implies that some benefit great or
+small is thus derived."</p>
+
+<h3>SIMILAR EFFECTS OF NATURAL SELECTION AND
+USE-INHERITANCE.</h3>
+
+<p>Here we perceive a difficulty which will equally
+trouble those who affirm use-inheritance and those<span class='pagenum'><a name="Page_84" id="Page_84">[84]</a></span>
+who deny. Broadly speaking, the adaptive effects
+ascribed to use-inheritance coincide with the effects
+of natural selection. The individual adaptability
+(as shown in the thickening of skin, fur, muscle,
+&amp;c., under the stimulus of friction, cold, use, &amp;c.)
+is identical in kind and direction with the racial
+adaptability under natural selection. Consequently
+the alleged inheritance of the advantageous effects
+of use and disuse cannot readily be distinguished
+from the similarly beneficial effects of natural
+selection. The indisputable fact that natural
+selection imitates or simulates the beneficial
+effects ascribed to use-inheritance may be the chief
+source and explanation of a belief which may prove
+to be thoroughly fallacious. A similar simulation
+of course occurs under domestication, where natural
+selection is partly replaced by artificial selection
+of the best adapted and therefore most flourishing
+animals, while in disused parts panmixia or the
+comparative cessation of selection will aid or<span class='pagenum'><a name="Page_85" id="Page_85">[85]</a></span>
+replace "economy of growth" in causing diminution.<a name="FNanchor_45_45" id="FNanchor_45_45"></a><a href="#Footnote_45_45" class="fnanchor">[45]</a></p>
+
+<h3>INFERIORITY OF SENSES IN EUROPEANS.</h3>
+
+<p>"The inferiority of Europeans, in comparison
+with savages, in eyesight and in the other senses,"
+is attributed to "the accumulated and transmitted
+effect of lessened use during many generations."<a name="FNanchor_46_46" id="FNanchor_46_46"></a><a href="#Footnote_46_46" class="fnanchor">[46]</a>
+But why may we not attribute it to the slackened
+and diverted action of the natural selection which
+keeps the senses so keen in some savage races?</p>
+
+<h3>SHORT-SIGHT IN WATCHMAKERS AND
+ENGRAVERS.</h3>
+
+<p>Darwin notices that watchmakers and engravers
+are liable to be short-sighted, and that short-sight<span class='pagenum'><a name="Page_86" id="Page_86">[86]</a></span>
+and long-sight certainly tend to be inherited.<a name="FNanchor_47_47" id="FNanchor_47_47"></a><a href="#Footnote_47_47" class="fnanchor">[47]</a> But
+we must be careful not to beg the question at issue
+by assuming that the frequent heredity of short
+sight necessarily covers the heredity of artificially-produced
+short-sight. Elsewhere, however, Darwin
+states more decisively that "there is ground for
+believing that it may often originate in causes
+acting on the individual affected, and may thence-forward
+become transmissible."<a name="FNanchor_48_48" id="FNanchor_48_48"></a><a href="#Footnote_48_48" class="fnanchor">[48]</a> This impression
+may arise (1) from the facts of ordinary heredity&mdash;the
+ancestral liability being excited in father and
+son by similar artificial habits, such as reading, and
+viewing objects closely as among watchmakers and
+engravers&mdash;or by constitutional deterioration from
+indoor life, &amp;c., acting upon a constitutional liability
+of the eye to the "something like inflammation
+of the coats, under which they yield" and so<span class='pagenum'><a name="Page_87" id="Page_87">[87]</a></span>
+cause shortness of sight by altering the spherical
+shape of the eye-ball. (2) Panmixia, or the suspension
+of natural selection, together with altered
+habits, will account for an increase of short-sight
+among the population generally. (3) Long-sighted
+people could not work at watchmaking
+and engraving so comfortably and advantageously
+as at other occupations, and hence would be less
+likely to take to such callings.</p>
+
+<h3>LARGER HANDS OF LABOURERS' INFANTS.<a name="FNanchor_49_49" id="FNanchor_49_49"></a><a href="#Footnote_49_49" class="fnanchor">[49]</a></h3>
+
+<p>These are best explained as the result of natural
+selection and of the diminution of the hand by
+sexual selection in the gentry. If the larger hands
+of labourers' infants are really due to the inherited
+effects of ancestral use, why does the development
+occur so early in life, instead of only at a corresponding
+period, as is the rule? During the first<span class='pagenum'><a name="Page_88" id="Page_88">[88]</a></span>
+few years of its life, at least, the labourer's infant
+does no more work than the gentleman's child.
+Why are not the effects of this disuse inherited
+by the labourer's infant? If the enlargement of the
+infant's hand illustrates the transference of a
+character gained later in life, it is evident that the
+transference must take place in spite of the inherited
+effects of disuse.</p>
+
+<h3>THICKENED SOLE IN INFANTS.</h3>
+
+<p>Darwin also attributes the thickened sole in infants,
+"long before birth," to "the inherited effects
+of pressure during a long series of generations."<a name="FNanchor_50_50" id="FNanchor_50_50"></a><a href="#Footnote_50_50" class="fnanchor">[50]</a>
+But disuse should make the infant's sole <i>thin</i>, and
+it is this thinness that should be inherited. If we
+suppose the inheritance of the thickened soles of
+later life to be transferred to an earlier period, we
+have the anomaly of the inherited effects of disuse<span class='pagenum'><a name="Page_89" id="Page_89">[89]</a></span>
+at that earlier period being overpowered by the
+untimely inheritance of the effects of use at another.
+On the other hand, it is clear that natural selection
+would favour thickened soles for walking on, and
+might also promote an early development which
+would ensure their being ready in good time for
+actual use; for variations in the direction of delay
+would be cut off, while variations in the other
+direction would be preserved. Anyhow, the mere
+transference of a character to an earlier period is
+no proof of use-inheritance. The real question is
+whether the thickened sole was gained by natural
+selection or by the inherited effects of pressure, and
+the mere transference or hastened appearance of
+the thickening does not in any degree solve this
+question. It merely excludes the effect of disuse
+during lifetime, and thus presents a fallacious appearance
+of being decisive. The thickened sole of
+the unborn infant, however, like the lanugo or
+hairy covering, is probably a result of the direct<span class='pagenum'><a name="Page_90" id="Page_90">[90]</a></span>
+inheritance of ancestral stages of evolution, of
+which the embryo presents a condensed epitome.
+While the relative thinness of the infant's sole
+might be pointed to as the effect of <i>disuse</i> during a
+long series of generations, its thickness is rather an
+illustration of atavism still resisting the effects of
+long-continued disuse. There is nothing to show
+that the inheritable portion of the full original
+thickness was not gained by natural selection
+rather than by the directly inherited effect of use;
+and the latter, being cumulative and indiscriminative
+in its action, would apparently have made
+the sole very much thicker and harder than it
+is. If natural selection were not supreme in such
+cases, how could we account for the effects of
+pressure resulting in hard hoofs in some cases and
+only soft pads in others?</p>
+
+<p><span class='pagenum'><a name="Page_91" id="Page_91">[91]</a></span></p>
+<h3>A SOURCE OF MENTAL CONFUSION.</h3>
+
+<p>Of course in a certain sense this thickening
+of the sole has resulted from use. In one sense
+or other, most&mdash;or perhaps all&mdash;of the results
+of natural selection are inherited effects of use
+or disuse. Natural selection preserves that
+which is of use and which is used, while it
+eliminates that which is useless and is not used.
+The most confident assertions of the effects of use
+and disuse in modifying the heritable type, appear
+to rest on this indefeasible basis. Darwin's statements
+concerning the effects of use and disuse in
+evolution can frequently be read in two senses.
+They often command assent as undeniable truisms
+as they stand, but are of course written in another
+and more debatable sense. Thus in the case of the
+shortened wings and thickened legs of the domestic
+duck, I believe equally with Darwin and Spencer
+that "no one will dispute that they have resulted<span class='pagenum'><a name="Page_92" id="Page_92">[92]</a></span>
+from the lessened use of the wings and the increased
+use of the legs." "Use" is at bottom the
+determining circumstance in evolution generally.
+The trunk of the elephant, the fin of the fish, the
+wing of the bird, the cunning hand of man and his
+complicated brain&mdash;and, in short, all organs and
+faculties whatsoever&mdash;can only have been moulded
+and developed by use&mdash;by usefulness and by using&mdash;but
+not necessarily by use-inheritance, not necessarily
+by directly inherited effects of use or
+disuse of parts in the individual. So, too, reduced
+or rudimentary organs are due to disuse, but it by
+no means follows that the diminution is caused by
+any direct tendency to the inheritance of the effects
+of disuse in the individual. The effects of natural
+selection are commonly expressible as effects of use
+and disuse, just as adaptation in nature is expressible
+in the language of teleology. But use-inheritance
+is no more proven by one of these necessary
+coincidences than special design is by the other.<span class='pagenum'><a name="Page_93" id="Page_93">[93]</a></span>
+The inevitable simulation of use-inheritance may
+be entirely deceptive.</p>
+
+<p>Darwin thinks that "there can be no doubt that
+use in our domestic animals has strengthened and
+enlarged certain parts, and disuse diminished
+them; and that such modifications are inherited."
+Undoubtedly "such" or <i>similar</i> modifications have
+often been inherited, but how can Darwin possibly
+tell that they are not due to the simulation of use-inheritance
+by natural or artificial selection acting
+upon general variability? Of the inevitability of
+selection and of its generally adaptive tendencies
+"there can be no doubt," and panmixia would tend
+to reduce disused parts; so that there <i>must always</i>
+remain grave doubts of the alleged inheritance of
+the similar effects of use and disuse, unless we can
+accomplish the extremely difficult feat of excluding
+both natural and artificial selection as causes
+of enlargement, and panmixia and selection as
+causes of dwindling.</p>
+
+<p><span class='pagenum'><a name="Page_94" id="Page_94">[94]</a></span></p>
+<h3>WEAKNESS OF USE-INHERITANCE.</h3>
+
+<p>Use-inheritance is normally so weak that it
+appears to be quite helpless when opposed to any
+other factor of evolution. Natural selection evolves
+and maintains the instincts of ants and termites
+in spite of use-inheritance to a more wonderful
+degree than it evolves the instincts of almost any
+other animal with the fullest help of use-inheritance.
+It develops seldom-used horns or natural
+armour just as readily as constantly-used hoofs or
+teeth. Sexual selection evolves elaborate structures
+like the peacock's tail in spite of disuse and natural
+selection combined. Artificial selection appears to
+enlarge or diminish used parts or disused parts with
+equal facility. The assistance of use-inheritance
+seems to be as unnecessary as its opposition is
+ineffective.</p>
+
+<p>The alleged inheritance of the effects of use
+and disuse in our domestic animals must be very<span class='pagenum'><a name="Page_95" id="Page_95">[95]</a></span>
+slow and slight.<a name="FNanchor_51_51" id="FNanchor_51_51"></a><a href="#Footnote_51_51" class="fnanchor">[51]</a> Darwin tells us that "there is
+no good evidence that this ever follows in the
+course of a single generation." "Several generations<span class='pagenum'><a name="Page_96" id="Page_96">[96]</a></span>
+must be subjected to changed habits for any
+appreciable result."<a name="FNanchor_52_52" id="FNanchor_52_52"></a><a href="#Footnote_52_52" class="fnanchor">[52]</a> What does this mean?
+One of two things. Either the tendency is
+very weak, or it is non-existent. If it is so
+weak that we cannot detect its alleged effects
+till several generations have elapsed, during which
+time the more powerful agency of selection has
+been at work, how are we to distinguish the effects
+of the minor factor from that of the major? Are
+we to conclude that use-inheritance <i>plus</i> selection
+will modify races, just as Voltaire firmly held that
+incantations, together with sufficient arsenic, would
+destroy flocks of sheep? Is it not a significant
+fact that the alleged instances of use-inheritance
+so often prove to be self-conflicting in their
+details?</p>
+
+<p>For satisfactory proof of the prevalence of a
+law of use-inheritance we require normal instances<span class='pagenum'><a name="Page_97" id="Page_97">[97]</a></span>
+where selection is clearly inadequate to produce
+the change, or where it is scarcely allowed
+time or opportunity to act, as in the immediate
+offspring of the modified individual. Of the
+first kind of cases there seems to be a plentiful
+lack. Of the latter kind, according to Darwin,
+there appears to be none&mdash;a circumstance which
+contrasts strangely and suspiciously with the
+many decisive cases in which variation from
+unknown causes has been inherited most strikingly
+in the immediate offspring. It must be
+expected, indeed, that among these innumerable
+cases some will accidentally mimic the
+alleged effects of use-inheritance.</p>
+
+<p>If Darwin had felt certain that the effects
+of habit or use tended in any marked degree
+to be conveyed directly and cumulatively to
+succeeding generations, he could hardly have
+given us such cautious, half-hearted encouragement
+of good habits as the following:&mdash;"It<span class='pagenum'><a name="Page_98" id="Page_98">[98]</a></span>
+is not improbable that after long practice virtuous
+tendencies may be inherited." "Habits, moreover
+followed during many generations probably tend
+to be inherited."<a name="FNanchor_53_53" id="FNanchor_53_53"></a><a href="#Footnote_53_53" class="fnanchor">[53]</a> This is probable, independently
+of use-inheritance. The "many generations"
+specified or implied, will allow time for the
+play of selective as well as of cumulatively-educative
+influences. There must apparently
+be a constitutional or inheritable predisposition
+or fitness for the habits spoken of, which otherwise
+would scarcely be continued for many
+generations, except by the favourably-varying
+branches of a family: which again is selection
+rather than use-inheritance.</p>
+
+<p>Where is the necessity for even the remains
+of the Lamarckian doctrine of inherited habit?
+Seeing how powerful the general principle of
+selection has shown itself in cases where use-inheritance
+could have given no aid or must<span class='pagenum'><a name="Page_99" id="Page_99">[99]</a></span>
+even have offered its most strenuous opposition,
+why should it not equally be able to develop used
+organs or repress disused organs or faculties
+without the assistance of a relatively weak ally?
+Selection evolved the remarkable protective
+coverings of the armadillo, turtle, crocodile, porcupine,
+hedgehog, &amp;c.; it formed alike the rose
+and its thorn, the nut and its shell; it developed
+the peacock's tail and the deer's antlers, the
+protective mimicry of various insects and
+butterflies, and the wonderful instincts of the
+white ants; it gave the serpent its deadly
+poison and the violet its grateful odour; it
+painted the gorgeous plumage of the Impeyan
+pheasant and the beautiful colours and decorations
+of countless birds and insects and flowers.
+These, and a thousand other achievements, it
+has evidently accomplished without the help of
+use-inheritance. Why should it be thought incapable
+of reducing a pigeon's wing or enlarging<span class='pagenum'><a name="Page_100" id="Page_100">[100]</a></span>
+a duck's leg? Why should it be credited with the
+help of an officious ally in effecting comparatively
+slight changes, when great and
+striking modifications are effected without any
+such aid?</p>
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote"><p><a name="Footnote_15_15" id="Footnote_15_15"></a><a href="#FNanchor_15_15"><span class="label">[15]</span></a> Weismann's <i>Essays on Heredity</i>, &amp;c. Clarendon Press,
+1889.</p></div>
+
+<div class="footnote"><p><a name="Footnote_16_16" id="Footnote_16_16"></a><a href="#FNanchor_16_16"><span class="label">[16]</span></a> <i>Life and Letters</i>, i. p. 16. Darwin's reverence for his father
+"was boundless and most touching. He would have wished to
+judge everything else in the world dispassionately, but anything his
+father had said was received with almost implicit faith; ... he
+hoped none of his sons would ever believe anything because he said
+it, unless they were themselves convinced of its truth&mdash;a feeling in
+striking contrast with his own manner of faith" (<i>Life and Letters</i>,
+i. pp. 10, 11).</p></div>
+
+<div class="footnote"><p><a name="Footnote_17_17" id="Footnote_17_17"></a><a href="#FNanchor_17_17"><span class="label">[17]</span></a> <i>Ibid.</i>, i. p. 38.</p></div>
+
+<div class="footnote"><p><a name="Footnote_18_18" id="Footnote_18_18"></a><a href="#FNanchor_18_18"><span class="label">[18]</span></a> <i>Life and Letters</i>, ii. p. 14.</p></div>
+
+<div class="footnote"><p><a name="Footnote_19_19" id="Footnote_19_19"></a><a href="#FNanchor_19_19"><span class="label">[19]</span></a> <i>Origin of Species</i>, pp. 117, 118.</p></div>
+
+<div class="footnote"><p><a name="Footnote_20_20" id="Footnote_20_20"></a><a href="#FNanchor_20_20"><span class="label">[20]</span></a> <i>Ibid.</i>, p. 180.</p></div>
+
+<div class="footnote"><p><a name="Footnote_21_21" id="Footnote_21_21"></a><a href="#FNanchor_21_21"><span class="label">[21]</span></a> <i>Contemporary Review</i>, December, 1875, pp. 89, 93.</p></div>
+
+<div class="footnote"><p><a name="Footnote_22_22" id="Footnote_22_22"></a><a href="#FNanchor_22_22"><span class="label">[22]</span></a> <i>Variation of Animals and Plants under Domestication</i>, i. 292.</p></div>
+
+<div class="footnote"><p><a name="Footnote_23_23" id="Footnote_23_23"></a><a href="#FNanchor_23_23"><span class="label">[23]</span></a> <i>Variation of Animals and Plants under Domestication</i>, i. 299-301.</p></div>
+
+<div class="footnote"><p><a name="Footnote_24_24" id="Footnote_24_24"></a><a href="#FNanchor_24_24"><span class="label">[24]</span></a> To keep pace with this lateral increase in weight, the leg-bones
+should have lengthened considerably so that their total deficiency
+in proportional length is 17 per cent.,&mdash;a changed proportion which
+being <i>linear</i> is more excessive than the increase of weight by
+28 per cent. So marked is the effect of the combined thickening
+and shortening that in the Aylesbury breed&mdash;which is the most
+typically representative one&mdash;the leg-bones have become 70 per cent.
+heavier than they should be if their thickness had continued to be
+proportional to their length.</p></div>
+
+<div class="footnote"><p><a name="Footnote_25_25" id="Footnote_25_25"></a><a href="#FNanchor_25_25"><span class="label">[25]</span></a> This excessive thickening under disuse appears to be due partly
+to a positive lateral enlargement or increase of proportional weight
+of about 7&frac12; per cent., and partly to a shortening of about 15 per
+cent. Carefully calculated, the reduction of the weight of the wing-bones
+in this breed is only 8&middot;3 per cent. relatively to the whole
+skeleton, or only 5 per cent. relatively to the skeleton <i>minus</i> legs
+and wings. The latter method is the more correct, since the excessive
+weight of the leg-bones increases the weight of the skeleton
+more than the diminished weight of the wing-bones reduces it.</p></div>
+
+<div class="footnote"><p><a name="Footnote_26_26" id="Footnote_26_26"></a><a href="#FNanchor_26_26"><span class="label">[26]</span></a> <i>Variation of Animals and Plants under Domestication</i>, i. 284.</p></div>
+
+<div class="footnote"><p><a name="Footnote_27_27" id="Footnote_27_27"></a><a href="#FNanchor_27_27"><span class="label">[27]</span></a> <i>Variation of Animals and Plants under Domestication</i>, i.
+184, 185.</p></div>
+
+<div class="footnote"><p><a name="Footnote_28_28" id="Footnote_28_28"></a><a href="#FNanchor_28_28"><span class="label">[28]</span></a> <i>Ibid.</i>, i. 144, 145.</p></div>
+
+<div class="footnote"><p><a name="Footnote_29_29" id="Footnote_29_29"></a><a href="#FNanchor_29_29"><span class="label">[29]</span></a> <i>Ibid.</i>, i. 185.</p></div>
+
+<div class="footnote"><p><a name="Footnote_30_30" id="Footnote_30_30"></a><a href="#FNanchor_30_30"><span class="label">[30]</span></a> <i>Variation of Animals and Plants under Domestication</i>, i. 175.</p></div>
+
+<div class="footnote"><p><a name="Footnote_31_31" id="Footnote_31_31"></a><a href="#FNanchor_31_31"><span class="label">[31]</span></a> <i>Variation of Animals and Plants under Domestication</i>, i. 184.
+I suspect that Darwin was in poor health when he wrote this page.
+He nods at least four times in it. Twice he speaks of "twelve"
+breeds where he obviously should have said eleven.</p></div>
+
+<div class="footnote"><p><a name="Footnote_32_32" id="Footnote_32_32"></a><a href="#FNanchor_32_32"><span class="label">[32]</span></a> If a prominent breast is admired and selected by fanciers, the
+sternum might shorten in assuming a more forward and vertical
+position. If the shortening of the sternum is entirely due to disuse,
+it seems strange that Darwin has not noticed any similar shortening
+in the sternum of the duck. But selection has not tended to make
+the duck elegant, or "pigeon-breasted"; it has enlarged the abdominal
+sack instead, besides allowing the addition of an extra rib in
+various cases.</p></div>
+
+<div class="footnote"><p><a name="Footnote_33_33" id="Footnote_33_33"></a><a href="#FNanchor_33_33"><span class="label">[33]</span></a> <i>Variation of Animals and Plants under Domestication</i>, 144, 175.</p></div>
+
+<div class="footnote"><p><a name="Footnote_34_34" id="Footnote_34_34"></a><a href="#FNanchor_34_34"><span class="label">[34]</span></a> <i>Variation of Animals and Plants under Domestication</i>, i.
+179.</p></div>
+
+<div class="footnote"><p><a name="Footnote_35_35" id="Footnote_35_35"></a><a href="#FNanchor_35_35"><span class="label">[35]</span></a> In the six largest breeds the shortening of the sternum is nearly
+twice as great as in the three smaller breeds which remain nearest
+the rock-pigeon in size. We can hardly suppose that use-inheritance
+especially affects the eight breeds that have varied most in size.
+If we exclude these, there is only a total shortening of 7 per cent. to
+be accounted for.</p></div>
+
+<div class="footnote"><p><a name="Footnote_36_36" id="Footnote_36_36"></a><a href="#FNanchor_36_36"><span class="label">[36]</span></a> <i>Variation of Animals and Plants under Domestication</i>, i. 183,
+186.</p></div>
+
+<div class="footnote"><p><a name="Footnote_37_37" id="Footnote_37_37"></a><a href="#FNanchor_37_37"><span class="label">[37]</span></a> <i>Variation of Animals and Plants under Domestication</i>, i. 130,
+135; ii. 288.</p></div>
+
+<div class="footnote"><p><a name="Footnote_38_38" id="Footnote_38_38"></a><a href="#FNanchor_38_38"><span class="label">[38]</span></a> <i>Encyclop&aelig;dia Britannica</i>, article "Zoology."</p></div>
+
+<div class="footnote"><p><a name="Footnote_39_39" id="Footnote_39_39"></a><a href="#FNanchor_39_39"><span class="label">[39]</span></a> <i>Variation of Animals and Plants under Domestication</i>, ii.
+367.</p></div>
+
+<div class="footnote"><p><a name="Footnote_40_40" id="Footnote_40_40"></a><a href="#FNanchor_40_40"><span class="label">[40]</span></a> <i>Variation of Animals and Plants under Domestication</i>, ii. 367.
+Why then does the cheetah inherit ancestral habits so inadequately
+that it is useless for the chase unless it has first learned to
+hunt for itself before being captured? (ii. 133).</p></div>
+
+<div class="footnote"><p><a name="Footnote_41_41" id="Footnote_41_41"></a><a href="#FNanchor_41_41"><span class="label">[41]</span></a> <i>Descent of Man</i>, p. 33.</p></div>
+
+<div class="footnote"><p><a name="Footnote_42_42" id="Footnote_42_42"></a><a href="#FNanchor_42_42"><span class="label">[42]</span></a> <i>Origin of Species</i>, pp. 210, 211.</p></div>
+
+<div class="footnote"><p><a name="Footnote_43_43" id="Footnote_43_43"></a><a href="#FNanchor_43_43"><span class="label">[43]</span></a> E. S. Delamer on <i>Pigeons and Rabbits</i>, pp. 132, 103. For
+other points referred to, see pages 133, 102, 100, 95, 131.</p></div>
+
+<div class="footnote"><p><a name="Footnote_44_44" id="Footnote_44_44"></a><a href="#FNanchor_44_44"><span class="label">[44]</span></a> <i>Origin of Species</i>, pp. 188, 110; <i>Descent of Man</i>, pp. 32-35;
+<i>Variation of Animals and Plants under Domestication</i>, ii. 289,
+293. Use or disuse during lifetime of course co-operates, and in
+some cases, as in that of the canoe Indians, may be the principal
+or even perhaps the <i>sole</i> cause of the change.</p></div>
+
+<div class="footnote"><p><a name="Footnote_45_45" id="Footnote_45_45"></a><a href="#FNanchor_45_45"><span class="label">[45]</span></a> For the importance of panmixia as invalidating Darwin's
+strongest evidence for use-inheritance&mdash;namely, that drawn from the
+effects of disuse in highly-fed domestic animals where there is
+supposed to be no economy of growth&mdash;see Professor Romanes on
+Panmixia, <i>Nature</i>, April 3, 1890.</p></div>
+
+<div class="footnote"><p><a name="Footnote_46_46" id="Footnote_46_46"></a><a href="#FNanchor_46_46"><span class="label">[46]</span></a> <i>Descent of Man</i>, p. 33.</p></div>
+
+<div class="footnote"><p><a name="Footnote_47_47" id="Footnote_47_47"></a><a href="#FNanchor_47_47"><span class="label">[47]</span></a> <i>Descent of Man</i>, p. 33.</p></div>
+
+<div class="footnote"><p><a name="Footnote_48_48" id="Footnote_48_48"></a><a href="#FNanchor_48_48"><span class="label">[48]</span></a> <i>Variation of Animals and Plants under Domestication</i>, i.,
+453.</p></div>
+
+<div class="footnote"><p><a name="Footnote_49_49" id="Footnote_49_49"></a><a href="#FNanchor_49_49"><span class="label">[49]</span></a> <i>Descent of Man</i>, p. 33.</p></div>
+
+<div class="footnote"><p><a name="Footnote_50_50" id="Footnote_50_50"></a><a href="#FNanchor_50_50"><span class="label">[50]</span></a> <i>Descent of Man</i>, p. 33.</p></div>
+
+<div class="footnote"><p><a name="Footnote_51_51" id="Footnote_51_51"></a><a href="#FNanchor_51_51"><span class="label">[51]</span></a> Wallace shows that the changes in our domestic animals, if
+spread over the thousands of years since the animals were first
+tamed, must be extremely insignificant in each generation, and he
+concludes that such infinitesimal effects of use and disuse would be
+swallowed up by the far greater effects of variation and selection
+(<i>Darwinism</i>, p. 436). Professor Romanes has replied to him in the
+<i>Contemporary Review</i> (August 1889), showing that this is no disproof
+of the existence of the minor factor, inasmuch as slight changes in
+each generation need not necessarily be matters of life and death to
+the individual, although their cumulative development by use-inheritance
+might eventually become of much service. But selection
+would favour spontaneous variations of a similarly serviceable
+character. The slightest tendency to eliminate the extreme
+variations in either direction would proportionally modify the
+average in a breed. Use-inheritance appears to be so relatively
+weak a factor that probably neither proof nor disproof of its
+existence can ever be given, owing to the practical impossibility of
+disentangling its effects (if any) from the effects of admittedly far
+more powerful factors which often act in unsuspected ways. Thus
+wild ducklings, which can easily be reared by themselves, invariably
+"die off" if reared with tame ones (<i>Variation</i>, &amp;c., i. 292, ii. 219).
+They cannot get their fair share in the competition for food, and are
+completely eliminated. Professor Romanes fully acknowledges
+that there is the "gravest possible doubt" as to the transmission of
+the effects of disuse (Letter on Panmixia, <i>Nature</i>, March 13, 1890).</p></div>
+
+<div class="footnote"><p><a name="Footnote_52_52" id="Footnote_52_52"></a><a href="#FNanchor_52_52"><span class="label">[52]</span></a> <i>Variation of Animals and Plants under Domestication</i>, ii.
+287-289.</p></div>
+
+<div class="footnote"><p><a name="Footnote_53_53" id="Footnote_53_53"></a><a href="#FNanchor_53_53"><span class="label">[53]</span></a> <i>Descent of Man</i>, pp. 612, 131.</p></div>
+</div>
+
+<hr /><p><span class='pagenum'><a name="Page_101" id="Page_101">[101]</a></span></p>
+<h2>INHERITED INJURIES.</h2>
+
+<h3>INHERITED MUTILATIONS.</h3>
+
+<p class="noin"><span class="smcap">The</span> almost universal <i>non-inheritance</i> of mutilations
+seems to me a far more valid argument
+<i>against</i> a general law of modification-inheritance
+than the few doubtful or abnormal cases of
+such inheritance can furnish in its favour.
+No inherited effect has been produced by the
+docking of horses' tails for many generations, or
+by a well-known mutilation which has been
+practised by the Hebrew race from time immemorial.
+As lost or mutilated parts are reproduced
+in offspring independently of the existence of
+those parts in the parent, there is the less reason<span class='pagenum'><a name="Page_102" id="Page_102">[102]</a></span>
+to suppose that the particular condition of
+parental parts transmits itself, or tends to
+transmit itself, to the offspring. So unsatisfactory
+is the argument derivable from inherited
+mutilations that Mr. Spencer does not mention
+them at all, and Darwin has to attribute them
+to a special cause which is independent of any
+general theory of use-inheritance.<a name="FNanchor_54_54" id="FNanchor_54_54"></a><a href="#Footnote_54_54" class="fnanchor">[54]</a></p>
+
+<p>Darwin's most striking case&mdash;and to my mind
+the only case of any importance&mdash;is that of Brown-S&eacute;quard's
+epileptic guinea-pigs, which inherited the
+mutilated condition of parents who had gnawed
+off their own gangrenous toes when an&aelig;sthetic
+through the sciatic nerve having been divided.<span class='pagenum'><a name="Page_103" id="Page_103">[103]</a></span><a name="FNanchor_55_55" id="FNanchor_55_55"></a><a href="#Footnote_55_55" class="fnanchor">[55]</a>
+Darwin also mentions a cow that lost a horn by
+accident, followed by suppuration, and subsequently
+produced three calves which had on the
+same side of the head, instead of a horn, a
+bony lump attached merely to the skin. Such
+cases may seem to prove that mutilation
+<i>associated with morbid action</i> is occasionally
+inherited or repeated with a promptitude and
+thoroughness that contrast most strikingly with
+the imperceptible nature of the immediate inheritance
+of the effects of use and disuse; but they
+by no means prove that mutilation in general
+is inheritable, and they are absolutely no proof
+whatever of a <i>normal</i> and non-pathological tendency
+to the inheritance of acquired characters.
+Those who accept Darwin's special explanation<span class='pagenum'><a name="Page_104" id="Page_104">[104]</a></span>
+of the supposed inheritance of mutilations, ought
+to notice that his explanation applies equally well
+under a theory which is strongly adverse to
+use-inheritance&mdash;namely, Galton's idea of the
+sterilization and complete "using up" of otherwise
+reproductive matter in the growth and
+maintenance of the personal structure.</p>
+
+<p>Darwin's explanation of inherited mutilations&mdash;which,
+as he notes, occur "especially or perhaps
+exclusively" when the injury has been followed
+by disease<a name="FNanchor_56_56" id="FNanchor_56_56"></a><a href="#Footnote_56_56" class="fnanchor">[56]</a>&mdash;is that all the representative
+gemmules which would develop or repair or
+reproduce the injured part are attracted to the
+diseased surface during the reparative process
+and are there destroyed by the morbid action.<span class='pagenum'><a name="Page_105" id="Page_105">[105]</a></span><a name="FNanchor_57_57" id="FNanchor_57_57"></a><a href="#Footnote_57_57" class="fnanchor">[57]</a>
+Hence they cannot reproduce the part in offspring.
+This explanation by no means implies
+that mutilation would <i>usually</i> affect the offspring.
+On the contrary, in all ordinary cases of mutilation
+the purely atavistic elements or gemmules would
+be set free from any modifying influence of the
+non-existent or mutilated part. The gemmules&mdash;as
+in Galton's theory of heredity and with neuter
+insects&mdash;might be perfectly independent of pangenesis
+and the normal inheritance of acquired
+characters. Such self-multiplying gemmules without
+pangenesis would enable us to understand
+both the excessive weakness or non-existence of
+normal use-inheritance, and the excessive strength
+and abruptness of the effect of their partial destruction
+under special pathological conditions.</p>
+
+<p>The series of epileptic phenomena that can be
+excited by tickling a certain part of the cheek
+and neck of the adult guinea-pig during the growth
+and rejoining of the ends of the severed nerve,<span class='pagenum'><a name="Page_106" id="Page_106">[106]</a></span>
+are said to be repeated with striking accuracy of
+detail in the young who inherit mutilated toes;
+but as epilepsy is often due to some <i>one</i> exciting
+cause or morbid condition, the single transmission
+of a highly morbid condition of the system might
+easily reproduce the whole chain of consequences
+and might also have caused the loss of toes.</p>
+
+<p>The particulars of the guinea-pig cases are
+very inadequately recorded,<a name="FNanchor_58_58" id="FNanchor_58_58"></a><a href="#Footnote_58_58" class="fnanchor">[58]</a> but the results are so
+anomalous<a name="FNanchor_59_59" id="FNanchor_59_59"></a><a href="#Footnote_59_59" class="fnanchor">[59]</a> that Brown-S&eacute;quard's own conclusion<span class='pagenum'><a name="Page_107" id="Page_107">[107]</a></span>
+is that the epilepsy and the inherited injuries are
+<i>not</i> directly transmitted, but that "what is
+transmitted is the morbid state of the nervous
+system." He thinks that the missing toes may
+"possibly" be exceptions to this conclusion,
+"but the other facts only imply the transmission
+of a morbid state of the sympathetic or sciatic
+nerve or of a part of the medulla oblongata."
+Until we can tell what is transmitted, we are not
+in a position to determine whether there is any
+true inheritance or only an exaggerated simulation
+of it under peculiar circumstances. When the
+actual observers believe that the mutilations and
+epilepsy are not the cause of their own repetition,<span class='pagenum'><a name="Page_108" id="Page_108">[108]</a></span>
+and when these observers guard themselves by
+such phrases as, "if any conclusion can at present
+be drawn from those facts," we who have only
+incomplete reports to guide us may well be
+excused if we preserve an even more pronounced
+attitude of caution and reserve.<a name="FNanchor_60_60" id="FNanchor_60_60"></a><a href="#Footnote_60_60" class="fnanchor">[60]</a> The morbid state
+of the system may be wholly due to general injury
+of the germs rather than to specific inheritance.</p>
+
+<p>Weismann suggests that the morbid condition
+of the nervous system may be due to some
+infection such as might arise from microbes, which
+find a home in the mutilated and disordered
+nervous system in the parent, and subsequently
+transmit themselves to the offspring through the
+reproductive elements, as the infections of various
+diseases appear to do&mdash;the muscardine silkworm<span class='pagenum'><a name="Page_109" id="Page_109">[109]</a></span>
+disease in particular being known to be conveyed
+to offspring in this manner.</p>
+
+<p>But whether we can discover the true explanation
+or not, inherited mutilations can hardly
+be accounted for as the result of a general
+tendency to inherit acquired modifications.
+How could a factor which seems to be totally
+inoperative in cases of ordinary mutilation, and
+only infinitesimally operative in transmitting the
+normal effects of use and disuse, suddenly become
+so powerful as to completely overthrow atavism,
+and its own tendency to transmit the non-mutilated
+type of one of the parents and of
+the non-mutilated type presented by the injured
+parent in earlier life? Does not so striking and
+abrupt an intensification of its usually insignificant
+power demand an explanation widely different
+from that which might account for the extremely
+slow and slight inheritance of the normal effects
+of use and disuse? Surely it would be better to<span class='pagenum'><a name="Page_110" id="Page_110">[110]</a></span>
+suspend one's judgment as to the true explanation
+of highly exceptional and purely pathological cases
+rather than resort to an hypothesis that creates more
+difficulties than it solves.</p>
+
+<h3>THE MOTMOT'S TAIL.</h3>
+
+<p>The narrowing of the long central tail
+feathers of the motmot is attributed to the inherited
+effects of habitual mutilation (<i>Descent of
+Man</i>, pp. 384, 603). But in the specimens at South
+Kensington<a name="FNanchor_61_61" id="FNanchor_61_61"></a><a href="#Footnote_61_61" class="fnanchor">[61]</a> the narrowness extends upwards
+much beyond the habitually denuded part, and the
+broadened end is the broadest part of the whole
+feather. If the inherited effect of an inch or
+two of denudation extends from three to six inches
+upwards, why has it not also extended two inches
+downwards so as to narrow the broadened end?<span class='pagenum'><a name="Page_111" id="Page_111">[111]</a></span>
+The narrowness seems to be a mainly relative or
+negative effect produced by the broadening out
+of a long tapering feather at its end under the
+influence of sexual selection. Several other birds
+have similarly narrowed or spoon-shaped feathers
+and do not bite them. Is it not more feasible to
+suppose that this attractive peculiarity first suggested
+its artificial intensification, than to suppose
+that the bird began nibbling without any definite
+cause? Sexual selection would then encourage
+the habit. Anyhow, it is as impossible to show
+that the mutilation preceded the narrowing as it
+is to show that tonsure preceded baldness.</p>
+
+<h3>OTHER INHERITED INJURIES MENTIONED BY
+DARWIN.</h3>
+
+<p>Darwin quotes some cases from Dr. Prosper
+Lucas's "long" but weak and unsatisfactory "list<span class='pagenum'><a name="Page_112" id="Page_112">[112]</a></span>
+of inherited injuries."<a name="FNanchor_62_62" id="FNanchor_62_62"></a><a href="#Footnote_62_62" class="fnanchor">[62]</a> But Lucas was somewhat
+credulous. One of his cases is that many girls
+were born in London without mamm&aelig; through the
+injurious effect of certain corsets on the mothers.
+He also gives a long account of a Jew who could
+read through the thick covers of a book, and whose
+son inherited this "hyper&aelig;sthesia" of the sense
+of sight in a still more remarkable degree (i.
+113-119). Evidently Lucas's cases cannot be
+accepted without some amount of reserve.</p>
+
+<p>The cases of the three calves which inherited
+the one-horned condition of the cow, the two sons
+who inherited a father's crooked finger, and the two
+sons who were microphthalmic on the same side
+as their father had lost an eye, may be due to
+mere coincidence; or an inherited constitutional
+tendency or liability might lead to somewhat similar<span class='pagenum'><a name="Page_113" id="Page_113">[113]</a></span>
+results in parent and offspring<a name="FNanchor_63_63" id="FNanchor_63_63"></a><a href="#Footnote_63_63" class="fnanchor">[63]</a>&mdash;just as the tendency
+to certain fatal diseases or to suicide may
+produce similar results in father and son, although
+the artificially-produced hanging or apoplexy obviously
+cannot be directly transmitted. That more
+than one of the offspring was affected does not
+render the chances against coincidence "almost infinitely
+great," as Darwin mistakenly supposes. It
+"frequently occurs" that a man's sons or daughters
+may <i>all</i> exhibit either a latent or a newly-developed
+congenital peculiarity previously unknown;<a name="FNanchor_64_64" id="FNanchor_64_64"></a><a href="#Footnote_64_64" class="fnanchor">[64]</a> and
+the coincidence may merely be that one of the
+parents accidentally suffered a similar kind of injury&mdash;a
+kind of coincidence which must of course
+occasionally occur, and which may have been
+partly caused by a latent tendency. The chances<span class='pagenum'><a name="Page_114" id="Page_114">[114]</a></span>
+against coincidence are indeed great, but the cases
+appear to be correspondingly rare.</p>
+
+<p>Darwin acknowledges that many supposed
+instances of inherited mutilation may be due
+to coincidence; and there is apparently no more
+reason for attributing inherited scars, &amp;c., to
+any special form of heredity than to the effect of
+the mother's imagination on the unborn babe&mdash;a
+popular but fallacious belief in corroboration of
+which far more alleged instances could be collected
+than of the inheritance of injuries.</p>
+
+<p>As an instance of the coincidences that occur,
+I may mention that a friend of mine has a
+daughter who was born with a small hole in one
+ear, just as if it were already pierced for the earring
+which she has since worn in it. I suppose,
+however, that no one will venture to claim
+this as an instance of the inheritance of a
+mutilation practised by female ancestors, especially
+as such holes are not altogether unknown or<span class='pagenum'><a name="Page_115" id="Page_115">[115]</a></span>
+inexplicable, though very rarely occurring low
+down in the lobe of the ear.<a name="FNanchor_65_65" id="FNanchor_65_65"></a><a href="#Footnote_65_65" class="fnanchor">[65]</a></p>
+
+<p>Many cases are known of the inheritance of
+mutilations or malformations arising congenitally
+from some abrupt variation in the reproductive
+elements. In such cases as the one-eared rabbits,
+the two-legged pigs, the three-legged dogs, the
+one-horned stags, hornless bulls, earless rabbits,
+lop-eared rabbits, tailless dogs, &amp;c., if the
+father or the mother or the embryo had suffered
+from some accident or disease which might plausibly
+have been assigned as the cause of the
+original malformation, these transmitted defects
+would readily be cited as instances of the
+inheritance of an accidentally-produced modification.</p>
+
+<p>The inheritance of exostoses on horses' legs may
+be the inheritance of a constitutional tendency<span class='pagenum'><a name="Page_116" id="Page_116">[116]</a></span>
+rather than of the effect of the parents' hard
+travelling. Horses congenitally liable to such
+formations would transmit the liability,<a name="FNanchor_66_66" id="FNanchor_66_66"></a><a href="#Footnote_66_66" class="fnanchor">[66]</a> and
+this might readily be mistaken for inheritance of
+the results of the liability. An apparent increase
+in this liability might arise from greater attention
+being now paid to it, or from increased use of
+harder roads; or a real increase might be due to
+panmixia and some obscure forms of correlation.</p>
+
+<h3>QUASI-INHERITANCE.</h3>
+
+<p>Of course artificially-caused ill-health or weakness
+in parents will tend in a general way to
+injure the offspring. But deterioration thus
+caused is only a form of quasi-inheritance, as I
+should prefer to call it. Semi-starvation in a new-born
+babe is <i>not</i> truly inherited from its half-starved
+mother, but is the direct result of insufficient<span class='pagenum'><a name="Page_117" id="Page_117">[117]</a></span>
+nourishment. The general welfare of germs&mdash;as of
+parasites&mdash;is necessarily bound up with that of
+the organism which feeds and shelters them, but
+this is not heredity, and is quite irrelevant to the
+question whether particular modifications are
+transmitted or not.</p>
+
+<p>Another form of quasi-inheritance is seen in the
+communication of certain infections to offspring.
+Not being transmitted by the action of the organism
+so much as in defiance of it, such diseases
+are not truly hereditary, though for convenience'
+sake they are usually so described.</p>
+
+<p>A perversion or prevention of true inheritance
+is also seen in the action of alcohol, or excessive
+overwork, or any other cause which by originating
+morbid conditions in individuals may also injure
+the reproductive elements.</p>
+
+<p>These forms of quasi-inheritance are, of course,
+highly important so far as the improvement of
+the race is concerned. So, too, is the fact that<span class='pagenum'><a name="Page_118" id="Page_118">[118]</a></span>
+improved or deteriorated habits and thoughts are
+transmitted by personal teaching and influence and
+are cumulative in their effect. But all this must
+not be confounded with the inheritance of acquired
+characters. Cases of quasi-inheritance
+may perhaps be most readily distinguished from
+cases of true inheritance by the time test. When
+a modification acquired in adult life is promptly
+communicated to the child in early life or from
+birth, it may rightly be suspected that the inheritance,
+like that of money or title, is not truly
+congenital, but is extraneous or even anti-congenital
+in its nature. Judged by such a standard,
+the inherited injuries in Brown-S&eacute;quard's
+guinea-pigs are only exceptional cases of quasi-inheritance,
+and are not necessarily indicative
+of any general rule affecting true inheritance.</p>
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote"><p><a name="Footnote_54_54" id="Footnote_54_54"></a><a href="#FNanchor_54_54"><span class="label">[54]</span></a> A very able anatomist of my acquaintance denies the inheritance
+of mutilations and injuries, although he strongly believes in the
+inheritance of the effects of use and disuse.</p></div>
+
+<div class="footnote"><p><a name="Footnote_55_55" id="Footnote_55_55"></a><a href="#FNanchor_55_55"><span class="label">[55]</span></a> <i>Variation of Animals and Plants under Domestication</i>, i. 467-469.
+Lost toes were only seen by Dr. Dupuy in three young out
+of two hundred. Obersteiner found that most of the offspring of
+his epileptic guinea-pigs were injuriously affected, being weakly,
+small, paralysed in one or more limbs, and so forth. Only two
+were epileptic, and both were weakly and died early (Weismann's
+<i>Essays</i>, p. 311). A morbid condition of the spinal cord might affect
+the hind limbs especially (as in paraplegia) and might occasionally
+cause loss of toes in the embryo by preventing development or by
+ulceration. Brown-S&eacute;quard does not say that the defective feet
+were on the same side as in the parents (<i>Lancet</i>, Jan., 1875, pp. 7, 8).</p></div>
+
+<div class="footnote"><p><a name="Footnote_56_56" id="Footnote_56_56"></a><a href="#FNanchor_56_56"><span class="label">[56]</span></a> <i>Variation of Animals and Plants under Domestication</i>, ii.
+57.</p></div>
+
+<div class="footnote"><p><a name="Footnote_57_57" id="Footnote_57_57"></a><a href="#FNanchor_57_57"><span class="label">[57]</span></a> <i>Ibid.</i>, ii. 392. Perhaps it might be better to suppose that the
+<i>best</i> gemmules were sacrificed in repairing the injured <i>nerve</i>, and
+hence only inferior substitutes were left to take their place, and
+could only imperfectly reproduce the injured part of the nervous
+system in offspring.</p></div>
+
+<div class="footnote"><p><a name="Footnote_58_58" id="Footnote_58_58"></a><a href="#FNanchor_58_58"><span class="label">[58]</span></a> Hence perhaps Mr. Spencer's error in representing the
+epileptic liability as permanent and as coming on <i>after</i> healing
+(<i>Factors of Organic Evolution</i>, p. 27).</p></div>
+
+<div class="footnote"><p><a name="Footnote_59_59" id="Footnote_59_59"></a><a href="#FNanchor_59_59"><span class="label">[59]</span></a> It is not claimed that the imperfect foot was on the same side of
+the body as in the parent, and where parents had lost <i>all</i> the toes
+of a foot, or the whole foot, the few offspring affected usually had
+lost only two toes out of the three, or only a part of one or two
+or three toes. Sometimes the offspring had toes missing on <i>both</i>
+hind feet, although the parent was only affected in <i>one</i>. <i>One</i> diseased
+ear and eye in the parent was "generally" or "always" succeeded
+by <i>two</i> equally affected ears and eyes in the offspring (cf. <i>Pop.
+Science Monthly</i>, New York, xi. 334). The important law of
+inheritance at corresponding periods was also set aside. Gangrene
+or inflammation commenced in both ears and both eyes soon after
+birth (pointing possibly to infection of some kind); the epileptic
+period commenced "perhaps two months or more after birth," while
+the loss of toes had occurred before birth. In no case, as Weismann
+points out, is the original mutilation of the nervous system ever transmitted.
+Even where an extirpated ganglion was never regenerated
+in the parent, the offspring always regained the part in an apparently
+perfect condition. On the whole the conflicting results ought to be
+as puzzling to those who may attribute them to a universal tendency
+to inherit the exact condition of parents as they are to those who, like
+myself, are sceptical as to the existence of such a law or tendency.</p></div>
+
+<div class="footnote"><p><a name="Footnote_60_60" id="Footnote_60_60"></a><a href="#FNanchor_60_60"><span class="label">[60]</span></a> The various results need to be fully and impartially recorded,
+and they should also be well tested and confirmed in proportion as
+they appear improbable and contrary to general experience. Professor
+Romanes has been carrying out the necessary experiments for
+some time past.</p></div>
+
+<div class="footnote"><p><a name="Footnote_61_61" id="Footnote_61_61"></a><a href="#FNanchor_61_61"><span class="label">[61]</span></a> Natural History Museum, central hall, third recess on the
+left.</p></div>
+
+<div class="footnote"><p><a name="Footnote_62_62" id="Footnote_62_62"></a><a href="#FNanchor_62_62"><span class="label">[62]</span></a> <i>Trait&eacute; de l'H&eacute;r&eacute;dit&eacute;</i>, ii. 489; <i>Variation of Animals and Plants
+under Domestication</i>, i. 469. If injuries are inherited, why has the
+repeated rupture of the hymen produced no inherited effect?</p></div>
+
+<div class="footnote"><p><a name="Footnote_63_63" id="Footnote_63_63"></a><a href="#FNanchor_63_63"><span class="label">[63]</span></a> Compare the three cases of crooked fingers given in <i>Variation
+of Animals and Plants under Domestication</i>, ii. 55, 240.</p></div>
+
+<div class="footnote"><p><a name="Footnote_64_64" id="Footnote_64_64"></a><a href="#FNanchor_64_64"><span class="label">[64]</span></a> <i>Ibid.</i>, i. 460. Thus, where two brothers married two sisters all
+the seven children were perfect albinos, although none of the
+parents or their relatives were albinos. In another case the nine
+children of two sound parents were all born blind (ii. 322).</p></div>
+
+<div class="footnote"><p><a name="Footnote_65_65" id="Footnote_65_65"></a><a href="#FNanchor_65_65"><span class="label">[65]</span></a> See pp. 179-182, <i>Evolution and Disease</i>, by J. Bland Sutton, to
+whom and to our mutual friend Dr. D. Thurston I am indebted for
+information on various points.</p></div>
+
+<div class="footnote"><p><a name="Footnote_66_66" id="Footnote_66_66"></a><a href="#FNanchor_66_66"><span class="label">[66]</span></a> <i>Variation of Animals and Plants under Domestication</i>, ii. 290;
+i. 454.</p></div>
+</div>
+
+<hr /><p><span class='pagenum'><a name="Page_119" id="Page_119">[119]</a></span></p>
+<h2>MISCELLANEOUS CONSIDERATIONS.</h2>
+
+<h3>TRUE RELATION OF PARENTS AND OFFSPRING.</h3>
+
+<p class="noin"><span class="smcap">It</span> is difficult to entirely free ourselves from
+the flattering and almost universal idea that parents
+are true originators or creators of copies of
+themselves. But the main truth, if not the whole
+truth, is that they are merely the transmitters
+of types of which they and their offspring are
+alike more or less similarly moulded resultants.
+A parent is a trustee. He transmits, not himself
+and his own modifications, but the stock, the
+type, the representative elements, of which he is
+a product and a custodian in one. It seems<span class='pagenum'><a name="Page_120" id="Page_120">[120]</a></span>
+probable that he has no more definite or
+"particulate" influence over the reproductive
+elements within him than a mother over the
+embryo or a vessel over its cargo. Parent and
+offspring are like successive copies of books
+printed from the same "type." A battered
+letter in the "type" will display its effects in
+both earlier and later copies alike, but a purely
+extraneous or acquired flaw in the first copy is
+not necessarily repeated in subsequent copies. Unlike
+printer's type, however, the material source
+of heredity is of a fluctuating nature, consisting
+of competing elements derived from two parents
+and from innumerable ancestors.</p>
+
+<p>Galton compares parent and child to successive
+pendants on the same chain. Weismann
+likens them to successive offshoots thrown up by
+a long underground root or sucker. Such comparisons
+indicate the improbability of acquired
+modifications being transmitted to offspring.<span class='pagenum'><a name="Page_121" id="Page_121">[121]</a></span></p>
+
+<p>That parts are developed in offspring independently
+of those parts in parents is clear.
+Mutilated parents transmit parts which they do
+not possess. The offspring of young parents cannot
+inherit the later stages of life from parents who
+have not passed through them. Cases of remote
+reversion or atavism show that ancestral peculiarities
+can transmit themselves in a latent or
+undeveloped condition for hundreds or thousands
+of generations. Many obvious facts compelled
+Darwin to suppose that vast numbers of the reproductive
+gemmules in an individual are not thrown
+off by his own cells, but are the self-multiplying
+progeny of ancestral gemmules. Galton restricts
+the production of gemmules by the personal
+structure to a few exceptional cases, and would
+evidently like to dispense with pangenesis altogether,
+if he could only be sure that acquired
+characters are never inherited. Weismann entirely
+rejects pangenesis and the inheritance of<span class='pagenum'><a name="Page_122" id="Page_122">[122]</a></span>
+acquired characters. This enables him to explain
+heredity by his theory of the "Continuity
+of the Germ-plasm."<a name="FNanchor_67_67" id="FNanchor_67_67"></a><a href="#Footnote_67_67" class="fnanchor">[67]</a> Parent and offspring are
+alike successive products or offshoots of this
+persistent germ-substance, which obviously would
+not be correspondingly affected by modifications of
+parts in parents, and so would render the transmission
+of acquired characters impossible.</p>
+
+<p><span class='pagenum'><a name="Page_123" id="Page_123">[123]</a></span></p>
+<h3>INVERSE INHERITANCE.</h3>
+
+<p>Mr. Galton contends that the reproductive elements
+become sterile when used in forming and
+maintaining the individual, and that only a small
+proportion of them are so used.<a name="FNanchor_68_68" id="FNanchor_68_68"></a><a href="#Footnote_68_68" class="fnanchor">[68]</a> He holds that
+the next generation will be formed entirely, or
+almost entirely, from the residue of undeveloped
+germs, which, not having been employed in the
+structure and work of the individual, have been
+free to multiply and form the reproductive elements
+whence future individuals are derived. Hence the
+singular inferiority not infrequently displayed by
+the children of men of extraordinary genius,
+especially where the ancestry has been only of a
+mediocre ability. The valuable germs have been
+used up in the individual, and rendered sterile in
+the structure of his person. Hence, too, the "strong
+tendency to deterioration in the transmission of<span class='pagenum'><a name="Page_124" id="Page_124">[124]</a></span>
+every exceptionally gifted race." Mr. Galton's
+hypothesis "explains the fact of certain diseases
+skipping one or more generations," and it "agrees
+singularly well with many classes of fact;" and it
+is strongly opposed to the theory of use-inheritance.
+The elements which are used die almost universally
+without germ progeny: the germs which are <i>not</i>
+used are the great source of posterity. Hence,
+when the germs or gemmules which achieve development
+are either better or worse than the
+residue, the qualities transmitted to offspring will
+be of an inverse character. If brain-work attracts,
+develops <i>and sterilizes</i> the best gemmules, the
+ultimate effect of education on the intellect of
+posterity may differ from its immediate effect.</p>
+
+<h3>EARLY ORIGIN OF THE OVA.</h3>
+
+<p>As the ova are formed at as early a period
+as the rest of the maternal structure, Galton<span class='pagenum'><a name="Page_125" id="Page_125">[125]</a></span>
+notices that it seems improbable that they
+would be correspondingly affected by subsequent
+modifications of parental structure. Of
+course it is not certain that this is a valid
+argument. We know that the paternal half of
+the reproductive elements does not enter the
+ovum till a comparatively late stage in its history,
+and it is quite possible that maternal elements or
+gemmules may also enter the ovum from without.
+If reproductive elements were confined to one
+special part or organ, we should be unable to explain
+the reproduction of lost limbs in salamanders,
+and the persistent effect of intercrossing on subsequent
+issue by the same mother, and the propagation
+of plants from shoots, or of the begonia from
+minute fragments of leaves, or the development of
+small pieces of water-worms into complete animals.</p>
+
+<p><span class='pagenum'><a name="Page_126" id="Page_126">[126]</a></span></p>
+<h3>MARKED EFFECTS OF USE AND DISUSE ON THE
+INDIVIDUAL.</h3>
+
+<p>These are, to some extent, an argument against
+the cumulative inheritance of such effects. When
+a nerve atrophies from disuse, or a duct shrivels,
+or bone is absorbed, or a muscle becomes small or
+flabby, it proves, so far, that the average effect of
+use through enormous ages is <i>not</i> transmitted.
+When the fibula of a dog's leg thickens by 400 per
+cent. to a size "equal to or greater than" that of
+the removed tibia which previously did the work,<a name="FNanchor_69_69" id="FNanchor_69_69"></a><a href="#Footnote_69_69" class="fnanchor">[69]</a>
+it shows that in spite of disuse for countless generations,
+the "almost filiform" bone has retained a
+potentiality of development which is fully equal to
+that possessed by the larger one which has been
+constantly used. When, after being reared on the
+ailanthus, the caterpillars of the <i>Bombyx hesperus</i><span class='pagenum'><a name="Page_127" id="Page_127">[127]</a></span>
+die of hunger rather than return to their natural
+food, the inherited effect of ancestral habit does
+not seem to be particularly strong. Neither is
+there any strongly-inherited effect of long-continued
+ancestral wildness in many animals which
+are easily tamed.</p>
+
+<h3>WOULD NATURAL SELECTION FAVOUR USE-INHERITANCE?</h3>
+
+<p>If use-inheritance is really one of the factors of
+evolution, it is certainly a subordinate one, and an
+utterly helpless one, whenever it comes into conflict
+with the great ruling principle of Selection.
+Would this dominant cause of evolution have
+favoured a tendency to use-inheritance if such
+had appeared, or would it have discouraged
+and destroyed it? We have already seen that
+use-inheritance is unnecessary, since natural selection
+will be far more effective in bringing<span class='pagenum'><a name="Page_128" id="Page_128">[128]</a></span>
+about advantageous modifications; and if it can
+be shown that use-inheritance would often be
+an evil, it then becomes probable that on the
+whole natural selection would more strongly discourage
+and eliminate it as a hostile factor than
+it might occasionally favour such a tendency as a
+totally unnecessary aid.</p>
+
+<h3>USE-INHERITANCE AN EVIL.</h3>
+
+<p>Use-inheritance would crudely and indiscriminately
+proportion parts to actual work done&mdash;or
+rather to the varying <i>nourishment and growth</i>
+resulting from a multiplicity of causes&mdash;and this
+in its various details would often conflict most
+seriously with the real necessities of the case,
+such as occasional passive strength, or appropriate
+shape, lightness and general adaptation. If its
+accumulated effects were not corrected by natural
+or sexual selection, horns and antlers would<span class='pagenum'><a name="Page_129" id="Page_129">[129]</a></span>
+disappear in favour of enlarged hoofs. The
+elephant's tusks would become smaller than its
+teeth. Men would have callosities for sitting
+on, like certain monkeys, and huge corns or
+hoofs for walking on. Bones would often be
+modified disastrously. Thus the condyle of the
+human jaw would become larger than the body
+of the jaw, because as the fulcrum of the lever
+it receives more pressure. Some organs (like the
+heart, which is always at work) would become
+inconveniently or unnecessarily large. Other
+absolutely indispensable organs, which are comparatively
+passive or are very seldom used,
+would dwindle until their weakness caused the
+ruin of the individual or the extinction of the
+species. In eliminating various evil results of use-inheritance,
+natural selection would be eliminating
+use-inheritance itself. The displacement of
+Lamarck's theory by Darwin's shows that the
+effects of use-inheritance often differ from those<span class='pagenum'><a name="Page_130" id="Page_130">[130]</a></span>
+required by natural selection; and it is clear that
+the latter factor must at least have reduced use-inheritance
+to the very minor position of comparative
+feebleness and harmlessness assigned to it
+by Darwin.</p>
+
+<p>Use-inheritance would be ruinous through
+causing unequal variation in co-operative parts&mdash;of
+which Mr. Spencer may accept his own instances
+of the jaws and teeth, and the cave-crab's
+lost eyes and persistent eye-stalks, as typical
+examples. That the variation would be unequal
+seems almost self-evident from the varying rapidity
+and extent of the effects of use and disuse on
+different tissues and on different parts of the
+general structure. The optic nerve may atrophy in
+a few months from disuse consequent on the loss
+of the eye. Some of the bones of the rudimentary
+hind legs of the whale are still in existence after
+disuse for an enormous period. Evidently use-inheritance
+could not equally modify the turtle<span class='pagenum'><a name="Page_131" id="Page_131">[131]</a></span>
+and its shell, or the brain and its skull; and in
+minor matters there would be the same incongruity
+of effect. Thus, if the molar teeth lengthened
+from extra use the incisors could not meet. Unequal
+and indiscriminate variation would throw
+the machinery of the organism out of gear in
+innumerable ways.</p>
+
+<p>Use-inheritance would perpetuate various evils.
+We are taught, for instance, that it perpetuates
+short-sight, inferior senses, epilepsy, insanity,
+nervous disorders, and so forth. It would apparently
+transmit the evil effects of over-exertion,
+disuse, hardship, exposure, disease and accident,
+as well as the defects of age or immaturity.</p>
+
+<p>Would it not be better on the whole if each
+individual took a fresh start as far as possible
+on the advantageous typical lines laid down by
+natural selection? Through the long stages of
+evolution from prim&aelig;val protoplasm upwards,
+such species as were least affected by use-inheritance<span class='pagenum'><a name="Page_132" id="Page_132">[132]</a></span>
+would be most free to develop necessary but
+seldom-used organs, protective coverings such as
+shells or skulls, and natural weapons, defences,
+ornaments, special adaptations, and so forth; and
+this would be an advantage&mdash;for survival would
+obviously depend on the <i>importance</i> of a structure
+or faculty in deciding the struggle for existence
+and reproduction, and not on the total amount
+of its using or nourishment. If natural selection
+had on the whole favoured this officious ally and
+frequent enemy, surely we should find better evidence
+of its existence.</p>
+
+<p>Without laying undue stress upon the evil
+effects of use-inheritance, a careful examination
+of them in detail may at least serve to counter-balance
+the optimistic <i>a priori</i> arguments for
+belief in that plausible but unproven factor of
+evolution.</p>
+
+<p>The benefits derivable from use-inheritance are
+largely illusory. The effects of <i>use</i>, indeed, are<span class='pagenum'><a name="Page_133" id="Page_133">[133]</a></span>
+generally beneficial up to a certain point; for
+natural selection has sanctioned or evolved organs
+which possess the property or potentiality of developing
+to the right extent under the stimulus
+of use or nourishment. But use-<i>inheritance</i> would
+cumulatively alter this individual adaptability,
+and would tend to fix the size of organs by the
+average amount of ancestral use or disuse rather
+than by the actual requirements of the individual.
+Of course under changed conditions involving
+increased or lessened use of parts it might
+become advantageous; but even here it may
+prove a decided hindrance to adaptive evolution in
+some respects as well as an unnecessary aid in
+others. Thus in the case of animals becoming
+heavier, or walking more, it would <i>lengthen</i> the
+legs although natural selection might require them
+to be shortened. In the Aylesbury duck and the
+Call duck, if use-inheritance has increased the
+dimensions of the bones and tendons of the leg,<span class='pagenum'><a name="Page_134" id="Page_134">[134]</a></span>
+natural selection has had to counteract this increase
+so far as length is concerned, and to effect 8 per
+cent. of shortening besides. If use-inheritance
+thickens bones without proportionally lengthening
+them, it would hinder rather than help the evolution
+of such structures as the long light wings of birds,
+or the long legs and neck of the giraffe or crane.</p>
+
+<h3>VARIED EFFECTS OF USE AND DISUSE.</h3>
+
+<p>The changes which we somewhat roughly
+and empirically group together as the effects of
+"use and disuse" are of widely diverse character.
+Thus bone, as the physiological fact, thickens under
+<i>alternations</i> of pressure (and the consequent
+increased flow of nourishment), but atrophies
+under a steadily continued pressure; so that if
+the use of a bone involved continuous pressure,
+the effect of such use would be a partial or total
+absorption of that bone. Darwin shows that<span class='pagenum'><a name="Page_135" id="Page_135">[135]</a></span>
+bone lengthens as well as thickens from carrying
+a greater weight, while tension (as seen in
+sailors' arms, which are used in pulling) appears to
+have an equally marked effect in shortening bones
+(<i>Descent of Man</i>, p. 32). Thus different kinds of
+use may produce opposite results. The cumulative
+inheritance of such effects would often be
+mischievous. The limbs of the sloth and the
+prehensile tail of the spider monkey would
+continually grow shorter, while the legs of the
+evolving elephant or rhinoceros might lengthen
+to an undesirable extent. Such cumulative
+tendencies of use-inheritance, if they exist, are
+obviously well kept under by natural selection.</p>
+
+<p>Although the ultimate effect of use is generally
+growth or enlargement through increased flow of
+blood, the first effect usually is a loss of substance,
+and a consequent diminution of size and strength.
+When the loss exceeds the growth, use will
+diminish or deteriorate the part used, while disuse<span class='pagenum'><a name="Page_136" id="Page_136">[136]</a></span>
+would enlarge or perfect it. Teeth, claws, nails,
+skin, hair, hoofs, feathers, &amp;c., may thus be worn
+away faster than they can renew themselves.
+But this wearing away usually stimulates the
+repairing process, and so increases the rate of
+growth; that is, it will increase the size produced,
+if not the size retained. Which effect of use does
+use-inheritance transmit in such cases&mdash;the increased
+rate of growth, or the dilapidation of the
+worn-out parts? We can hardly suppose that
+both these effects of use will be inherited. Would
+shaving destroy the beard in time or strengthen
+it? Will the continued shearing of sheep
+increase or lessen the growth of wool? What
+will be the ultimate effect of plucking geese's
+quills, and of the eider duck's abstraction of the
+down from her breast? If the mutilated parts
+grow stronger or more abundantly, why were
+the motmot's feathers alleged to be narrowed by
+the inherited effects of ancestral nibbling?<span class='pagenum'><a name="Page_137" id="Page_137">[137]</a></span></p>
+
+<p>The "use" or "work" or "function" of muscles,
+nerves, bones, teeth, skin, tendon, glands, ducts,
+eyes, blood corpuscles, cilia, and the other constituents
+of the organism, is as widely different as
+the various parts are from each other, and the
+effects of their use or disuse are equally varied
+and complicated.</p>
+
+<h3>USE-INHERITANCE IMPLIES PANGENESIS.</h3>
+
+<p>How could the transmission of these varied
+effects to offspring be accounted for? Is it possible
+to believe, with Mr. Spencer, that the effects
+of use and disuse on the parts of the personal
+structure are simultaneously registered in corresponding
+impressions on the seminal germs?
+Must we not feel, with Darwin apparently,<a name="FNanchor_70_70" id="FNanchor_70_70"></a><a href="#Footnote_70_70" class="fnanchor">[70]</a> that
+the <i>only</i> intelligible explanation of use-inheritance<span class='pagenum'><a name="Page_138" id="Page_138">[138]</a></span>
+is the hypothesis of Pangenesis, according to
+which each modified cell, or physiological unit,
+throws off similarly-modified gemmules or parts
+of itself, which ultimately reproduce the change
+in offspring? If we reject pangenesis, it becomes
+difficult to see how use-inheritance can be
+possible.</p>
+
+<h3>PANGENESIS IMPROBABLE.</h3>
+
+<p>The more important and best-known phenomena
+of heredity do not require any such
+hypothesis, and leading facts (such as atavism,
+transmission of lost parts, and the general non-transmission
+of acquired characters) are so adverse
+to it that Darwin has to concede that many of the
+reproductive gemmules are atavistic, and that by
+continuous self-multiplication they may preserve
+a practical "continuity of germ-substance," as
+Weismann would term it. The idea that the<span class='pagenum'><a name="Page_139" id="Page_139">[139]</a></span>
+relationship of offspring to parent is one of direct
+descent is, as Galton tells us, "wholly untenable";
+and the only reason he admits some supplementary
+traces of pangenesis into his "Theory of
+Heredity,"<a name="FNanchor_71_71" id="FNanchor_71_71"></a><a href="#Footnote_71_71" class="fnanchor">[71]</a> is that he may thus account for the
+more or less questionable cases of the transmission
+of acquired characters. But there appears
+to be no necessity even for this concession. We
+ought therefore to dispense with the useless and
+gratuitous hypothesis that cells multiply by
+throwing off minute self-multiplying gemmules, as
+well as by the well-known method of self-division.
+If pangenesis occurs, the transmission of acquired
+characters ought to be a prominent fact.
+The size, strength, health and other good or evil
+qualities of the cells could hardly fail to exercise
+a marked and corresponding effect upon the size
+and quality of the reproductive gemmules thrown
+off by those cells. The direct evidence tends to<span class='pagenum'><a name="Page_140" id="Page_140">[140]</a></span>
+show that these free gemmules do not exist. Transfusion
+of blood has failed to affect inheritance in
+the slightest degree. Pangenesis, with its attraction
+of gemmules from all parts of the body into the
+germ-cells, and the free circulation of gemmules
+in the offspring till they hit upon or are attracted
+by the particular cell or cells, with which alone
+they can readily unite, seems a less feasible theory
+and less in conformity with the whole of the facts
+than an hypothesis of germ-continuity which supposes
+that the development of the germ-plasm
+and of the successive self-dividing cells of the
+body proceeds from within. Darwin's keen
+analogy of the fertilization of plants by pollen
+renders development from without conceivable,
+but as there are no insects to convey gemmules to
+their destination, each kind of gemmule would
+have to be exceedingly numerous and easily attracted
+from amongst an inconceivable number of
+other gemmules. Arguments against pangenesis<span class='pagenum'><a name="Page_141" id="Page_141">[141]</a></span>
+can also be drawn from the case of neuter insects&mdash;a
+fact which seems to have escaped Darwin's
+notice, although he had seen how strongly that
+case was opposed to the doctrine which is the
+essential basis of the theory of pangenesis.</p>
+
+<h3>SPENCER'S EXPLANATION OF USE-INHERITANCE.</h3>
+
+<p>Mr. Spencer's explanation of the inheritance of
+the effects of use and disuse (p. 36) is that "while
+generating a modified <i>consensus</i> of functions and of
+structures, the activities are at the same time impressing
+this modified <i>consensus</i> on the sperm-cells
+and germ-cells whence future individuals are to be
+produced"&mdash;a proposition which reads more like
+metaphysics than science. Difficult to understand
+or believe in ordinary instances, such <i>consensus</i>-inheritance
+seems impossible in cases like that of
+the hive-bee. Can we suppose that the <i>consensus</i>
+of the activities of the working bee impresses<span class='pagenum'><a name="Page_142" id="Page_142">[142]</a></span>
+itself on the sperm-cells of the drones and on the
+germ-cells of the carefully secluded queen?
+B&uuml;chner thinks so, for he says: "Although the
+queens and drones do not now work, yet the
+capacities inherited from earlier times still remain to
+them, especially to the former, and are kept alive
+and fresh by the impressions constantly made upon
+them during life, and they are thus in a position to
+transmit them to posterity." Surely it is better
+to abandon a cherished theory than to be compelled
+to defend it by explanations which are as
+inconsistent as they are inadequate. New capacities
+are developed as well as old ones kept fresh.
+The massacre or expulsion of the drones would
+have to impress itself on the germ-cells of an onlooking
+queen, and the imprisonment of the
+queen on the sperm-cells of the drones&mdash;and in
+such a way, moreover, as to be afterwards developed
+into action in the neuters only. And
+use-inheritance all the while is being thoroughly<span class='pagenum'><a name="Page_143" id="Page_143">[143]</a></span>
+overpowered by impression-inheritance&mdash;by the
+full transmission of that which is merely seen in
+others! If such a law prevails, one may feel
+cold because an ancestor thought of the frosty
+Caucasus. None of this absurdity would arise if
+it were clearly seen that a parent is only a trustee&mdash;that
+transmission and development are perfectly
+distinct&mdash;that parental modifications are irrelevant
+to those transmitted to offspring.</p>
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote"><p><a name="Footnote_67_67" id="Footnote_67_67"></a><a href="#FNanchor_67_67"><span class="label">[67]</span></a> <i>Essays on Heredity</i>, p. 104. Weismann's theory is clear, simple
+and convenient, but incomplete; for, unlike Darwin's theory of
+pangenesis, it scarcely attempts any real explanation of the extremely
+complex potentialities possessed by the reproductive elements.
+Perhaps we might retain Darwin's self-multiplying gemmules without
+supposing them to be thrown off by the cells, which will no longer
+be credited with <i>two</i> modes of multiplication. These minute germs
+or gemmules may have been evolved by natural selection playing
+upon the sample germs that achieve development; and they may
+exist either separately, or (preferably but perhaps not invariably) in
+aggregates to form Weismann's germ-plasm.</p></div>
+
+<div class="footnote"><p><a name="Footnote_68_68" id="Footnote_68_68"></a><a href="#FNanchor_68_68"><span class="label">[68]</span></a> <i>Contemporary Review</i>, Dec., 1875, p. 88.</p></div>
+
+<div class="footnote"><p><a name="Footnote_69_69" id="Footnote_69_69"></a><a href="#FNanchor_69_69"><span class="label">[69]</span></a> <i>Variation of Animals and Plants under Domestication</i>, ii.
+286.</p></div>
+
+<div class="footnote"><p><a name="Footnote_70_70" id="Footnote_70_70"></a><a href="#FNanchor_70_70"><span class="label">[70]</span></a> <i>Variation of Animals and Plants under Domestication</i>, ii. 388,
+398, 367; <i>Life and Letters</i>, iii. 44.</p></div>
+
+<div class="footnote"><p><a name="Footnote_71_71" id="Footnote_71_71"></a><a href="#FNanchor_71_71"><span class="label">[71]</span></a> <i>Contemporary Review</i>, Dec., 1875, pp. 94, 95.</p></div>
+</div>
+
+<hr /><p><span class='pagenum'><a name="Page_144" id="Page_144">[144]</a></span></p>
+<h2>CONCLUSIONS.</h2>
+
+<h3>USE-INHERITANCE DISCREDITED AS UNNECESSARY,
+UNPROVEN, AND IMPROBABLE.</h3>
+
+<p class="noin"><span class="smcap">General</span> experience teaches that acquired
+characters are not usually inherited; and investigation
+shows that the apparent exceptions to
+this great rule are probably fallacious. Even the
+alleged instances of use-inheritance culled by such
+great and judicious selectors as Darwin and
+Spencer break down upon examination; for they
+can be better explained without use-inheritance
+than with it. On the other hand, the adverse
+facts and considerations are almost strong enough
+to prove the actual non-existence of such a law or<span class='pagenum'><a name="Page_145" id="Page_145">[145]</a></span>
+tendency. There is no need to undertake the
+apparently impossible task of demonstrating an
+absolute negative. It will be enough to ask that
+the Lamarckian factor of use-inheritance shall be
+removed from the category of accredited factors of
+evolution to that of unnecessary and improbable
+hypotheses. The main explanation or source of
+the fallacy may be found in the fact that natural
+selection frequently imitates some of the more
+obvious effects of use and disuse.</p>
+
+<h3>MODERN RELIANCE ON USE-INHERITANCE
+MISPLACED.</h3>
+
+<p>Modern philanthropy&mdash;so far at least as it ever
+studies ultimate results&mdash;constantly relies on this
+ill-founded belief as its justification for ignoring
+the warnings of those who point out the ultimately
+disastrous results of a systematic defiance
+or reversal of the great law of natural selection.<span class='pagenum'><a name="Page_146" id="Page_146">[146]</a></span>
+This reliance finds strong support in Mr. Spencer's
+latest teachings, for he holds that the inheritance
+of the effects of use and disuse takes place
+universally, and that it is now "the chief factor"
+in the evolution of civilized man (pp. 35, 74, iv)&mdash;natural
+selection being quite inadequate for the
+work of progressive modification. Practically he
+abandons the hope of evolution by natural selection,
+and substitutes the ideal of a nation being
+"modified <i>en masse</i> by transmission of the effects"
+of its institutions and habits. Use-inheritance
+will "mould its members far more rapidly and
+comprehensively" than can be effected by the
+survival of the fittest alone.</p>
+
+<p>But could we rely upon the aid of use-inheritance
+if it really were a universal law and not
+a mere simulation of one? Let us consider some
+of the features of this alleged factor of evolution,
+seeing that it is henceforth to be our principal
+means of securing the improvement of our species<span class='pagenum'><a name="Page_147" id="Page_147">[147]</a></span>
+and our continued adaptation to the changing
+conditions of a progressive civilization.</p>
+
+<p>It is curiously uncertain and irregular in its
+action. It diminishes or abolishes some structures
+(such as jaws or eyes) without correspondingly
+diminishing or abolishing other equally disused
+and closely related parts (such as teeth, or eye-stalks).
+It thickens ducks' leg-bones while allowing
+them to shorten. It shortens the disused
+wing-bones of ducks and the leg-bones of rabbits
+while allowing them to thicken; and yet in other
+cases it greatly reduces the thickness of bones
+without shortening them. It transmits tameness
+most powerfully in an animal which usually
+cannot acquire it. It aids in webbing the feet of
+water-dogs, but fails to web the feet of the water-hen
+or to remove the web in the feet of upland
+geese.<a name="FNanchor_72_72" id="FNanchor_72_72"></a><a href="#Footnote_72_72" class="fnanchor">[72]</a> It allows the disused fibula to retain a<span class='pagenum'><a name="Page_148" id="Page_148">[148]</a></span>
+potentiality of development fully equal to that
+possessed by the long-used tibia. It lengthens
+legs because they are used in supporting the
+body, and shortens arms because they are used
+in pulling. Whether it enlarges brain if used
+in one way and diminishes it if used in another,
+we cannot tell; but it must obviously deaden
+nervous sensibilities in some cases and intensify
+them in others. It enlarges hands long
+before they are used, and thickens soles long
+before the time for walking on them. At the
+same time, as if by an oversight, it so delays its
+transmission of the habit of walking on these
+thickened soles, that the gradual and tedious acquisition
+of the non-transmitted habit costs the
+infant much time and trouble and often some pain
+and danger. Yet where aided by natural selection,
+as with chickens and foals, it transmits the habit
+in wonderful perfection and at a remarkably
+early date. It transmits new paces in horses in<span class='pagenum'><a name="Page_149" id="Page_149">[149]</a></span>
+a single generation, but fails to perpetuate the
+songs of birds. It modifies offspring like parents,
+and yet allows the formation of two reproductive
+types in plants, and of two or more types widely
+different from the parents in some of the higher
+insects. It is said to be indispensable for the co-ordinated
+development of man and the giraffe
+and the elk, but appears to be unnecessary for the
+evolution and the maintenance of wonderful
+structures and habits and instincts in a thousand
+species of ants and bees and termites. It is the
+only possible means of complex evolution and
+adaptation of co-operative parts, and yet in
+Mr. Spencer's most representative case it renders
+such important parts as teeth and jaws unsuited
+for each other, and is said to ruin the teeth by the
+consequent overcrowding and decay. It survives
+amidst a general "lack of recognised evidence,"
+and only seems to act usefully and healthily and
+regularly in quarters where it can least easily be<span class='pagenum'><a name="Page_150" id="Page_150">[150]</a></span>
+distinguished from other more powerful and demonstrable
+factors of evolution. So little does it
+care to display its powers where they would be
+easily verifiable as well as useful that practical
+breeders ignore it. So slight is its independent
+power that it seems to allow natural selection or
+sexual selection or artificial selection to modify
+organisms in sheer defiance of its utmost opposition,
+just as readily as they modify organisms in
+other directions with its utmost help. If it
+partially perpetuates and extends the pecked-out
+indentations in the motmot's tail feathers, it on the
+other hand fails to transmit the slightest trace of
+mutilation in an almost infinite number of
+ordinary cases, and even where the mutilation is
+repeated for a hundred generations; and it
+apparently repairs rather than transmits the
+ordinary and oft-repeated losses caused by
+plucking hair, down and feathers, and the wear
+and tear of claws, teeth, hoofs and skin.</p>
+<p><span class='pagenum'><a name="Page_151" id="Page_151">[151]</a></span></p>
+<p>It is often mischievous as well as anomalous in
+its action. Under civilization with its division of
+labour, the various functions of mind and body are
+very unequally exercised. There is overwork or
+misuse of one part and disuse and neglect of others,
+leading to the partial breakdown or degeneration
+of various organs and to general deterioration of
+health through disturbed balance of the constitution.
+The brain, or rather particular parts of it, are
+often over-stimulated, while the body is neglected.
+In many ways education and civilization foster
+nervousness and weakness, and undermine the rude
+natural health and spirits of the human animal.
+Alcohol, tobacco, tea, coffee, extra brain work, late
+hours, dissipation, overwork, indoor life, division of
+labour, preservation of the weak, and many other
+causes, all help to injure the modern constitution;
+so that the prospect of cumulative intensification of
+these evils by the additional influence of use-inheritance
+is not an encouraging one. It is true<span class='pagenum'><a name="Page_152" id="Page_152">[152]</a></span>
+that modern progress and prosperity are improving
+the people in various respects by their direct action;
+but if use-inheritance has any share in effecting this
+improvement it must also transmit increased wants
+and more luxurious habits, together with such evils
+as have already been referred to. As depicted by
+its defenders, use-inheritance transmits evils far
+more powerfully and promptly than benefits. It
+transmits insanity and shattered nerves rather than
+the healthy brain which preceded the breakdown.
+It perpetuates, and cumulatively intensifies, a
+deterioration in the senses of civilized men, but it
+fails to perpetuate the rank vigour of various plants
+when too well nourished, or the flourishing condition
+of various animals when too fat or when tamed. It
+already transmits the short-sight caused by so
+modern an art as watchmaking, but so fails to
+transmit the long-practised art of seeing (as it does
+of walking and talking) that vision is worse than
+useless to a man until he gradually acquires the<span class='pagenum'><a name="Page_153" id="Page_153">[153]</a></span>
+necessary but non-transmitted associations of
+sensation and idea by his own experience. In a
+well-known case, a blind man on gaining his sight
+by an operation said that "all objects seemed
+to touch his eyes, as what he felt did his skin"&mdash;so
+little had the universal experience of countless ages
+impressed itself on his faculties. Under normal
+healthy conditions use-inheritance is so slow in
+its action that "several generations" must elapse
+before it produces any appreciable effect, and then
+that effect is only precisely what selection might be
+expected to bring about without its aid. Strong
+for evil and slow for good, it can convey epilepsy
+promptly in guinea pigs, but transmits the acquirements
+of genius so poorly that our best student
+of the heredity of genius has to account for the
+frequent and remarkable deterioration of the
+offspring by a theory which is strongly hostile to
+use-inheritance. It would tend to make organisms
+unworkable by the excessive differences in its rate<span class='pagenum'><a name="Page_154" id="Page_154">[154]</a></span>
+and manner of action on co-operative parts, and
+by adapting these parts to the total amount of
+nourishment received rather than to occasional
+necessity or actual usefulness. It would tend to
+stereotype habits and convert reason into instinct.</p>
+
+<p>How then can we rely upon use-inheritance for
+the improvement of the race? Even if it is not a
+sheer delusion, it may be more detrimental as a positive
+evil than it is advantageous as an unnecessary
+benefit; and as a normal modifying agent it is
+miserably weak and untrustworthy in comparison
+with the powerful selective influences by which
+nature and society continually and inevitably affect
+the species for good or for evil. The effects of use
+and disuse&mdash;rightly directed by education in its
+widest sense&mdash;must of course be called in to secure
+the highly essential but nevertheless <i>superficial,
+limited, and partly deceptive</i> improvement of individuals
+and of social manners and methods; but as
+this artificial development of already existing<span class='pagenum'><a name="Page_155" id="Page_155">[155]</a></span>
+potentialities does not directly or readily tend to
+become congenital, it is evident that some considerable
+amount of natural or artificial selection of the
+more favourably varying individuals will still be the
+only means of securing the race against the constant
+tendency to degeneration which would ultimately
+swallow up all the advantages of civilization. The
+selective influences by which our present high level
+has been reached and maintained may well be modified,
+but they must not be abandoned or reversed
+in the rash expectation that State education, or
+State feeding of children, or State housing of the
+poor, or any amount of State socialism or public
+or private philanthropy, will prove permanently
+satisfactory substitutes. If ruinous deterioration
+and other more immediate evils, are to be avoided,
+the race must still be to the swift and the battle to
+the strong. The healthy Individualism so earnestly
+championed by Mr. Spencer must be allowed free
+play. Open competition, as Darwin teaches, with<span class='pagenum'><a name="Page_156" id="Page_156">[156]</a></span>
+its survival and multiplication of the fittest, must
+be allowed to decide the battle of life independently
+of a foolish benevolence that prefers the elaborate
+cultivation and multiplication of weeds to the
+growth of corn and roses. We are trustees for the
+countless generations of the future. If we are wise
+we shall trust to the great ruling truths that we
+assuredly know, rather than to the seductive claims
+of an alleged factor of evolution for which no
+satisfactory evidence can be produced.</p>
+
+<div class="p4">THE END.</div>
+
+<div class="p4"><small>RICHARD CLAY AND SONS, LIMITED, LONDON AND BUNGAY.</small></div>
+
+<div class="footnotes"><h3>FOOTNOTES:</h3>
+
+<div class="footnote"><p><a name="Footnote_72_72" id="Footnote_72_72"></a><a href="#FNanchor_72_72"><span class="label">[72]</span></a> Professor Romanes had casts made of the feet of upland geese,
+and could not detect any diminution as compared with the web of
+other geese in relation to the toes.</p></div></div>
+
+<hr />
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+
+
+<pre>
+
+
+
+
+
+End of the Project Gutenberg EBook of Are the Effects of Use and Disuse
+Inherited?, by William Platt Ball
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@@ -0,0 +1,3256 @@
+The Project Gutenberg EBook of Are the Effects of Use and Disuse Inherited?, by
+William Platt Ball
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Are the Effects of Use and Disuse Inherited?
+       An Examination of the View Held by Spencer and Darwin
+
+Author: William Platt Ball
+
+Release Date: August 26, 2008 [EBook #26438]
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK THE EFFECTS OF USE AND DISUSE ***
+
+
+
+
+Produced by Bryan Ness, Stephen Blundell and the Online
+Distributed Proofreading Team at https://www.pgdp.net (This
+book was produced from scanned images of public domain
+material from the Google Print project.)
+
+
+
+
+
+
+
+
+
+ _NATURE SERIES_
+
+
+               ARE THE EFFECTS OF USE AND
+                    DISUSE INHERITED?
+
+           _AN EXAMINATION OF THE VIEW HELD BY
+                   SPENCER AND DARWIN_
+
+
+                           BY
+                   WILLIAM PLATT BALL
+
+
+                         LONDON
+                    MACMILLAN AND CO.
+                      AND NEW YORK
+                          1890
+
+ _The Right of Translation and Reproduction is Reserved_
+
+
+
+
+ RICHARD CLAY AND SONS, LIMITED,
+       LONDON AND BUNGAY.
+
+
+
+
+PREFACE.
+
+
+My warmest thanks are due to Mr. Francis Darwin, to Mr. E. B. Poulton
+(whose interest in the subject here discussed is shown by his share in
+the translation of Weismann's _Essays on Heredity_), and to Professor
+Romanes, for the help afforded by their kindly suggestions and
+criticisms, and for the advice and recommendation under which this essay
+is now published. Encouragement from Mr. Francis Darwin is to me the
+more precious, and the more worthy of grateful recognition, from the
+fact that my general conclusion that acquired characters are _not_
+inherited is at variance with the opinion of his revered father, who
+aided his great theory by the retention of some remains of Lamarck's
+doctrine of the inherited effect of habit. I feel as if the son, as
+representative of his great progenitor, were carrying out the idea of an
+appreciative editor who writes to me: "We must say that if Darwin were
+still alive, he would find your arguments of great weight, and
+undoubtedly would give to them the serious consideration which they
+deserve." I hope, then, that I may be acquitted of undue presumption in
+opposing a view sanctioned by the author of the _Origin of Species_, but
+already stoutly questioned and firmly rejected by such followers of his
+as Weismann, Wallace, Poulton, Ray Lankester, and others, to say nothing
+of its practical rejection by so great an authority on heredity as
+Francis Galton.
+
+The sociological importance of the subject has already been insisted on
+in emphatic terms by Mr. Herbert Spencer, and this importance may be
+even greater than he imagined.
+
+Civilization largely sets aside the harsh but ultimately salutary action
+of the great law of Natural Selection without providing an efficient
+substitute for preventing degeneracy. The substitute on which moralists
+and legislators rely--if they think on the matter at all--is the
+cumulative inheritance of the beneficial effects of education, training,
+habits, institutions, and so forth--the inheritance, in short, of
+acquired characters, or of the effects of use and disuse. If this
+substitute is but a broken reed, then the deeper thinkers who gradually
+teach the teachers of the people, and ultimately even influence the
+legislators and moralists, must found their systems of morality and
+their criticisms of social and political laws and institutions and
+customs and ideas on the basis of the Darwinian law rather than on that
+of Lamarck.
+
+Looking forward to the hope that the human race may become consciously
+and increasingly master of itself and of its destiny, and recognizing
+the Darwinian principle of the selection of the fittest as the _only_
+means of preventing the moral and physical degeneracy which, like an
+internal dry rot, has hitherto been the besetting danger of all
+civilizations, I desire that the thinkers who mould the opinions of
+mankind shall not be led astray from the true path of enduring progress
+and happiness by reliance on fallacious beliefs which will not bear
+examination. Such, at least, is the feeling or motive which has prompted
+me to devote much time and thought to a difficult but important inquiry
+in a debatable region of inference and conjecture, where (I am afraid)
+evidence on either side can never be absolutely conclusive, and where,
+especially, the absolute demonstration of a universal negative cannot
+reasonably be expected.
+
+
+
+
+CONTENTS.
+
+
+                                                                PAGE
+ PREFACE                                                           v
+
+ IMPORTANCE AND BEARING OF THE INQUIRY                             1
+
+ SPENCER'S EXAMPLES AND ARGUMENTS                               6-44
+   DIMINUTION OF THE JAWS                                          6
+   DIMINISHED BITING MUSCLES OF LAP-DOGS                          12
+   CROWDED TEETH                                                  14
+   BLIND CAVE-CRABS                                               17
+   NO CONCOMITANT VARIATION FROM CONCOMITANT DISUSE               17
+   THE GIRAFFE, AND NECESSITY FOR CONCOMITANT VARIATION           18
+   ALLEGED RUINOUS EFFECTS OF NATURAL SELECTION                   23
+   ADVERSE CASE OF NEUTER INSECTS                                 24
+   AESTHETIC FACULTIES                                             29
+   LACK OF EVIDENCE                                               34
+   INHERITED EPILEPSY IN GUINEA-PIGS                              35
+   INHERITED INSANITY AND NERVOUS DISORDERS                       36
+   INDIVIDUAL AND TRANSMISSIBLE TYPE NOT MODIFIED ALIKE           40
+
+ DARWIN'S EXAMPLES                                            45-100
+   REDUCED WINGS OF BIRDS OF OCEANIC ISLANDS                      49
+   DROOPING EARS AND DETERIORATED INSTINCTS                       53
+   WINGS AND LEGS OF DUCKS AND FOWLS                              55
+   PIGEONS' WINGS                                                 62
+   SHORTENED BREAST-BONE IN PIGEONS                               64
+   SHORTENED FEET IN PIGEONS                                      70
+   SHORTENED LEGS OF RABBITS                                      70
+   BLIND CAVE-ANIMALS                                             72
+   INHERITED HABITS                                               73
+   TAMENESS OF RABBITS                                            76
+   MODIFICATIONS OBVIOUSLY ATTRIBUTABLE TO SELECTION              82
+   SIMILAR EFFECTS OF NATURAL SELECTION AND USE-INHERITANCE       83
+   INFERIORITY OF SENSES IN EUROPEANS                             85
+   SHORT-SIGHT IN WATCHMAKERS AND ENGRAVERS                       85
+   LARGER HANDS OF LABOURERS' INFANTS                             87
+   THICKENED SOLE IN INFANTS                                      88
+   A SOURCE OF MENTAL CONFUSION                                   91
+   WEAKNESS OF USE-INHERITANCE                                    94
+
+ INHERITED INJURIES                                          101-118
+   INHERITED MUTILATIONS                                         101
+   THE MOTMOT'S TAIL                                             110
+   OTHER INHERITED INJURIES MENTIONED BY DARWIN                  111
+   QUASI-INHERITANCE                                             116
+
+ MISCELLANEOUS CONSIDERATIONS                                119-143
+   TRUE RELATION OF PARENTS AND OFFSPRING                        119
+   INVERSE INHERITANCE                                           123
+   EARLY ORIGIN OF THE OVA                                       124
+   MARKED EFFECTS OF USE AND DISUSE ON THE INDIVIDUAL            126
+   WOULD NATURAL SELECTION FAVOUR USE-INHERITANCE?               127
+   USE-INHERITANCE AN EVIL                                       128
+   VARIED EFFECTS OF USE AND DISUSE                              134
+   USE-INHERITANCE IMPLIES PANGENESIS                            137
+   PANGENESIS IMPROBABLE                                         138
+   SPENCER'S EXPLANATION OF USE-INHERITANCE                      141
+
+ CONCLUSIONS                                                 144-156
+   USE-INHERITANCE DISCREDITED AS UNNECESSARY, UNPROVEN,
+       AND IMPROBABLE                                            144
+   MODERN RELIANCE ON USE-INHERITANCE MISPLACED                  145
+
+
+
+
+ARE THE EFFECTS OF USE AND DISUSE INHERITED?
+
+
+
+
+IMPORTANCE AND BEARING OF THE INQUIRY.
+
+
+The question whether the effects of use and disuse are inherited, or, in
+other words, whether acquired characters are hereditary, is of
+considerable interest to the general student of evolution; but it is, or
+should be, a matter of far deeper interest to the thoughtful
+philanthropist who desires to ensure the permanent welfare and happiness
+of the human race. So profoundly important, in fact, are the moral,
+social, and political conclusions that depend on the answer to this
+inquiry, that, as Mr. Herbert Spencer rightly says, it "demands, beyond
+all other questions whatsoever, the attention of scientific men."
+
+It is obvious that we can produce important changes in the individual.
+We can, for example, improve his muscles by athletics, and his brain by
+education. The use of organs enlarges and strengthens them; the disuse
+of parts or faculties weakens them. And so great is the power of habit
+that it is proverbially spoken of as "second nature." It is thus certain
+that we can modify the individual. We can strengthen (or weaken) his
+body; we can improve (or deteriorate) his intellect, his habits, his
+morals. But there remains the still more important question which we are
+about to consider. Will such modifications be inherited by the offspring
+of the modified individual? Does individual improvement transmit itself
+to descendants independently of personal teaching and example? Have
+artificially produced changes of structure or habit any inherent
+tendency to become congenitally transmissible and to be converted in
+time into fixed traits of constitution or character? Can the
+philanthropist rely on such a tendency as a hopeful factor in the
+evolution of mankind?--the only sound and stable basis of a higher and
+happier state of things being, as he knows or ought to know, the innate
+and constitutionally-fixed improvement of the race as a whole. If
+acquired modifications are impressed on the offspring and on the race,
+the systematic moral training of individuals will in time produce a
+constitutionally moral race, and we may hope to improve mankind even in
+defiance of the unnatural selection by which a spurious but highly
+popular philanthropy would systematically favour the survival of the
+unfittest and the rapid multiplication of the worst. But if acquired
+modifications do not tend to be transmitted, if the use or disuse of
+organs or faculties does not similarly affect posterity by inheritance,
+then it is evident that no innate improvement in the race can take place
+without the aid of natural or artificial selection.
+
+Herbert Spencer maintains that the effects of use and disuse _are_
+inherited in kind, and in his _Factors of Organic Evolution_[1] he has
+supported his contention with a selection of facts and reasonings which
+I shall have the temerity to examine and criticize. Darwin also held the
+same view, though not so strongly. And here, to prevent
+misunderstanding, I may say that the admiration and reverence and
+gratitude due to Darwin ought not to be allowed to interfere in the
+slightest degree with the freest criticism of his conclusions. To
+perfect his work by the correction of really extraneous errors is as
+much a sacred duty as to study and apply the great truths he has taught.
+
+
+FOOTNOTES:
+
+[1] Which originally appeared in the _Nineteenth Century_ for April and
+May, 1886.
+
+
+
+
+SPENCER'S EXAMPLES AND ARGUMENTS.
+
+
+DIMINUTION OF THE JAWS IN CIVILIZED RACES.
+
+Mr. Spencer verified this by comparing English jaws with Australian and
+Negro jaws at the College of Surgeons.[2] He maintains that the
+diminution of the jaw in civilized races can _only_ have been brought
+about by inheritance of the effects of lessened use. But if English jaws
+are lighter and thinner than those of Australians and Negroes, so too is
+the rest of the skull. As the diminution in the weight and thickness of
+the walls of the cranium cannot well be ascribed to disuse, it must be
+attributed to some other cause; and this cause may have affected the jaw
+also. Cessation of the process by which natural selection[3] favoured
+strong thick bones during ages of brutal violence might bring about a
+change in this direction. Lightness of structure, facilitating agility
+and being economical of material, would also be favoured by natural
+selection so far as strength was not too seriously diminished.
+
+Sexual selection powerfully affects the human face, and so must affect
+the jaws--as is shown by the differences between male and female jaws,
+and by the relative lightness and smallness of the latter, especially in
+the higher races. Human preference, both sexual and social, would tend
+to eliminate huge jaws and ferocious teeth when these were no longer
+needed as weapons of war or organs of prehension, &c. We can hardly
+assume that the lower half of the face is specially exempt from the
+influence of natural and sexual selection; and the effects of these
+undoubted factors of evolution must be fully considered before we are
+entitled to call in the aid of a factor whose existence is questioned.
+
+After allowing for lost teeth and the consequent alveolar absorption,
+and for a reduction proportional to that shown in the rest of the skull,
+the difference in average weight in fifty European and fourteen
+Australian male jaws at the College of Surgeons turned out to be less
+than a fifth of an ounce, or about 5 per cent. This slight reduction may
+be much more than accounted for by such causes as disuse in the
+individual, human preference setting back the teeth, and partial
+transference of the much more marked diminution seen in female jaws.
+There is apparently no room for accumulated _inherited_ effects of
+ancestral disuse. The number of jaws is small, indeed; but weighing them
+is at least more decisive than Mr. Spencer's mere inspection.
+
+The differences between Anglo-Saxon male jaws and Australian and
+Tasmanian jaws are most easily explained as effects of human preference
+and natural selection. We can hardly suppose that disuse would maintain
+or develop the projecting chin, increase its perpendicular height till
+the jaw is deepest and strongest at its extremity, evolve a side flange,
+and enlarge the upper jaw-bone to form part of a more prominent nose,
+while drawing back the savagely obtrusive teeth and lips to a more
+pleasing and subdued position of retirement and of humanized beauty. If
+human preference and natural selection caused some of these differences,
+why are they incompetent to effect changes in the direction of a
+diminution of the jaw or teeth? And if use and disuse are the sole
+modifying agents in the case of the human jaw, why should men have any
+more chin than a gorilla or a dog?
+
+The excessive weight of the West African jaws at the College of Surgeons
+is partly _against_ Mr. Spencer's contention, unless he assumes that
+Guinea Negroes use their jaws far more than the Australians, a
+supposition which seems extremely improbable. The heavier skull and
+narrower molar teeth point however to other factors than increased use.
+
+The striking variability of the human jaw is strongly opposed to the
+idea of its being under the direct and dominant control of so uniform a
+cause as ancestral use and disuse. Mr. Spencer regards a variation of 1
+oz. as a large one, but I found that the English jaws in the College of
+Surgeons varied from 1.9 oz. to 4.3 oz. (or 5 oz. if lost teeth were
+allowed for); Australian jaws varied from 2 oz. to 4.5 oz. (with _no_
+lost teeth to allow for); while in Negro jaws the maximum rose to over
+5-1/2 oz.[4] In spite of disuse some European jaws were twice as heavy
+as the lightest Australian jaw, either absolutely or (in some cases)
+relatively to the cranium. The uniformity of change relied upon by Mr.
+Spencer is scarcely borne out by the facts so far as male jaws are
+concerned. The great reduction in the weight of _female_ jaws _and
+skulls_ evidently points to sexual selection and to panmixia under male
+protection.
+
+I think, on the whole, we must conclude that the human jaws do not
+afford satisfactory proof of the inheritance of the effects of use and
+disuse, inasmuch as the differences in their weight and shape and size
+can be more reasonably and consistently accounted for as the result of
+less disputable causes.
+
+
+DIMINISHED BITING MUSCLES OF LAP-DOGS.
+
+The next example, the reduced biting muscles, &c., of lap-dogs is also
+unsatisfactory as a proof of the inheritance of the effects of disuse;
+for the change can readily be accounted for without the introduction of
+such a factor. The previous natural selection of strong jaws and teeth
+and muscles is reversed. The conscious or unconscious selection of
+lap-dogs with the least tendency to bite would easily bring about a
+general enfeeblement of the whole biting apparatus--weakness of the
+parts concerned favouring harmlessness. Mr. Spencer maintains that the
+dwindling of the parts concerned in clenching the jaw is certainly not
+due to artificial selection because the modifications offer no
+appreciable external signs. Surely hard biting is sufficiently
+appreciable by the person bitten without any visual admeasurement of the
+masseter muscles or the zygomatic arches. Disuse during lifetime would
+also cause some amount of degeneracy; and I am not sure that Mr. Spencer
+is right in _entirely_ excluding economy of nutrition from the problem.
+Breeders would not over-feed these dogs; and the puppies that grew most
+rapidly would usually be favoured.
+
+
+CROWDED TEETH.
+
+The too closely-packed teeth in the "decreasing" jaws of modern men (p.
+13)[5] are also suggestive of other causes than use and disuse. Why is
+there not simultaneous variation in teeth and jaws, if disuse is the
+governing factor? Are we to suppose that the size of the human teeth is
+maintained by use at the same time that the jaws are being diminished by
+disuse? Mr. Spencer acknowledges that the crowding of bull-dogs' and
+lap-dogs' teeth is caused by the artificial selection of shortened jaws.
+If a similar change is really occurring in man, could it not be
+similarly explained by some factor, such as sexual selection, which
+might affect the outward appearance at the cost of less obvious defects
+or inconveniences?
+
+Mr. Spencer points to the decay of modern teeth as a sign or result of
+their being overcrowded through the diminution of the jaw by disuse.[6]
+But the teeth which are the most frequently overcrowded are the lower
+incisors. The upper incisors are less overcrowded, being commonly
+pressed outwards by the lower arc of teeth fitting inside them in
+biting. The lower incisors are correspondingly pressed inwards and
+closer together. Yet the upper incisors decay--or at least are
+extracted--about twenty times as frequently as the closely packed lower
+incisors.[7] Surely this must indicate that the cause of decay is not
+overcrowding.
+
+The lateness and irregularity of the wisdom teeth are sometimes
+supposed to indicate their gradual disappearance through want of room in
+a diminishing jaw. But a note on Tasmanian skulls in the _Catalogue of
+the College of Surgeons_ (p. 199) shows that this lateness and
+irregularity have been common among Tasmanians as well as among
+civilized races, so that the change can hardly be attributed to the
+effects of disuse under civilization.
+
+
+BLIND CAVE-CRABS.
+
+The cave-crabs which have lost their disused eyes but _not the disused
+eye-stalks_ appear to illustrate the effects of natural selection rather
+than of disuse. The loss of the exposed, sensitive, and
+worse-than-useless eye, would be a decided gain, while the disused
+eye-stalk, being no particular detriment to the crab, would be but
+slightly affected by natural selection, though open to the cumulative
+effects of disuse. The disused but better protected eyes of the blind
+cave-rat are still "of large size" (_Origin of Species_, p. 110).
+
+
+NO CONCOMITANT VARIATION FROM CONCOMITANT DISUSE.
+
+It is but fair to add that these instances of the cave-crab's eye-stalk
+and the closely-packed teeth are put forward by Mr. Spencer with the
+more immediate object of proving that there is "no concomitant
+variation in co-operative parts," even when "formed out of the same
+tissue, like the crab's eye and its peduncle" (pp. 12-14, 23, 33). It
+escapes his notice, however, that in two out of his three cases it is
+_disuse_, or _diminished use_, which fails to cause concomitant
+variation or proportionate variation.
+
+
+THE GIRAFFE, AND NECESSITY FOR CONCOMITANT VARIATION.
+
+Having unwittingly shown that lessened use of closely-connected and
+co-operative parts does not cause concomitant variation in these parts,
+Mr. Spencer concludes that the concomitant variation requisite for
+evolution can only be caused by altered degrees of use or disuse. He
+elaborately argues that the many co-ordinated modifications of parts
+necessitated by each important alteration in an animal are so complex
+that they cannot possibly be brought about except by the inherited
+effect of the use and disuse of the various parts concerned. He holds,
+for instance, that natural selection is inadequate to effect the
+numerous concomitant changes necessitated by such developments as that
+of the long neck of the giraffe. Darwin, however, on the contrary, holds
+that natural selection alone "would have sufficed for the production of
+this remarkable quadruped."[8] He is surprised at Mr. Spencer's view
+that natural selection can do so little in modifying the higher animals.
+Thus one of the chief arguments with which Mr. Spencer supports his
+theory is so poorly founded as to be rejected by a far greater authority
+on such subjects. All that is needed is that natural selection should
+preserve the tallest giraffes through times of famine by their being
+able to reach otherwise inaccessible stores of foliage. The continual
+variability of all parts of the higher animals gives scope for
+innumerable changes, and Nature is not in a hurry. Mr. Spencer, however,
+says that "the chances against any adequate readjustments fortuitously
+arising must be infinity to one." But he has also shown that altered
+degree of use does not cause the needed concomitant variation of
+co-operative parts. So the chances against a beneficial change in an
+animal must be, at a liberal estimate, infinity to two. Mr. Spencer, if
+he has proved anything, has proved that it is practically impossible
+that the giraffe can have acquired a long neck, or the elk its huge
+horns, or that any species has ever acquired any important modification.
+
+Mr. Wallace, in his _Darwinism_, answers Mr. Spencer by a collection of
+facts showing that "variation is the rule," that the range of variation
+in wild animals and plants is much greater than was supposed, and that
+"each part varies to a considerable extent independently" of other
+parts, so that "the materials constantly ready for natural selection to
+act upon are abundant in quantity and very varied in kind." While
+co-operative parts would often be more or less correlated, so that they
+would tend to vary together, coincident variation is not necessary. The
+lengthened wing might be gained in one generation, and the strengthened
+muscle at a subsequent period; the bird in the meanwhile drawing upon
+its surplus energy, aided (as I would suggest) by the strengthening
+effect of increased use in the individual. Seeing that artificial
+selection of complicated variations has modified animals in many points
+either simultaneously or by slow steps, as with otter-sheep, fancy
+pigeons, &c. (many of the characters thus obtained being clearly
+independent of use and disuse), natural selection must be credited with
+similar powers, and Mr. Wallace concludes that Mr. Spencer's
+insuperable difficulty is "wholly imaginary."
+
+The extract concerning a somewhat similar "class of difficulties," which
+Mr. Spencer quotes from his _Principles of Biology_, is faulty in its
+reasoning,[9] though legitimate in its conclusion concerning the
+increasing difficulty of evolution in proportion with the increasing
+number and complexity of faculties to be evolved. But this increasing
+difficulty of complex evolution is only overcome by _some_
+favourably-varying individuals and species--not by all. And as the
+difficulty increases we find neglect and decay of the less-needed
+faculties--as with domesticated animals and civilized men, who lose in
+one direction while they gain in another. The increasing difficulty of
+complex evolution by natural selection is no proof whatever of
+use-inheritance[10] except to those who confound difficulty with
+impossibility.
+
+
+ALLEGED RUINOUS EFFECTS OF NATURAL SELECTION.
+
+Mr. Spencer further contends that natural selection, by unduly
+developing specially advantageous modifications without the necessary
+but complex secondary modifications, would render the constitution of a
+variety "unworkable" (p. 23). But this seems hardly feasible, seeing
+that natural selection must continually favour the most workable
+constitutions, and will only preserve organisms in proportion as they
+combine general workableness with the special modification. On the other
+hand, according to Mr. Spencer himself, use-inheritance must often
+disturb the balance of the constitution. Thus it tends to make the jaws
+and teeth unworkable through the overcrowding and decay of the
+teeth--there being, as his illustrations show, no simultaneous or
+concomitant or proportional variation in relation to altered degree of
+use or disuse.
+
+
+ADVERSE CASE OF NEUTER INSECTS.
+
+Mr. Spencer also holds that most mental phenomena, especially where
+complex or social or moral, can only be explained as arising from
+use-inheritance, which becomes more and more important as a factor of
+evolution as we advance from the vegetable world and the lower grades of
+animal life to the more complex activities, tastes, and habits of the
+higher organizations (preface, and p. 74). But there happens to be a
+tolerably clear proof that such changes as the evolution of complicated
+structures and habits and social instincts _can_ take place
+independently of use-inheritance. The wonderful instincts of the working
+bees have apparently been evolved (at least in all their later social
+complications and developments) without the aid of use-inheritance--nay,
+in spite of its utmost opposition. Working bees, being infertile
+"neuters," cannot as a rule transmit their own modifications and habits.
+They are descended from countless generations of queen bees and drones,
+whose habits have been widely different from those of the workers, and
+whose structures are dissimilar in various respects. In many species of
+ants there are two, and in the leaf-cutting ants of Brazil there are
+_three_, kinds of neuters which differ from each other and from their
+male and female ancestors "to an almost incredible degree."[11] The
+soldier caste is distinguished from the workers by enormously large
+heads, very powerful mandibles, and "extraordinarily different"
+instincts. In the driver ant of West Africa one kind of neuter is three
+times the size of the other, and has jaws nearly five times as long. In
+another case "the workers of one caste alone carry a wonderful sort of
+shield on their heads." One of the three neuter classes in the
+leaf-cutting ants has a single eye in the midst of its forehead. In
+certain Mexican and Australian ants some of the neuters have huge
+spherical abdomens, which serve as living reservoirs of honey for the
+use of the community. In the equally wonderful case of the termites, or
+so-called "white ants" (which belong, however, to an entirely different
+order of insect from the ants and bees) the neuters are blind and
+wingless, and are divided into soldiers and workers, each class
+possessing the requisite instincts and structures adapting it for its
+tasks. Seeing that natural selection can form and maintain the various
+structures and the exceedingly complicated instincts of ants and bees
+and wasps and termites in direct defiance of the alleged tendency to
+use-inheritance, surely we may believe that natural selection,
+unopposed by use-inheritance, is equally competent for the work of
+complex or social or mental evolution in the many cases where the strong
+presumptive evidence cannot be rendered almost indisputable by the
+exceptional exclusion of the modified animal from the work of
+reproduction.
+
+Ants and bees seem to be capable of altering their habits and methods of
+action much as men do. Bees taken to Australia cease to store honey
+after a few years' experience of the mild winters. Whole communities of
+bees sometimes take to theft, and live by plundering hives, first
+killing the queen to create dismay among the workers. Slave ants attend
+devotedly to their captors, and fight against their own species. Forel
+reared an artificial ant-colony made up of five different and more or
+less hostile species. Why cannot a much more intelligent animal modify
+his habits far more rapidly and comprehensively without the aid of a
+factor which is clearly unnecessary in the case of the more intelligent
+of the social insects?
+
+
+AESTHETIC FACULTIES.
+
+The modern development of music and harmony (p. 19) is undeniable, but
+why could it only have been brought about by the help of the inheritance
+of the effects of use? Why are we to suppose that "minor traits" such as
+the "aesthetic perceptions" cannot have been evolved by natural selection
+(p. 20) or by sexual selection? Darwin holds that our musical faculties
+were developed by sexual preference long before the acquisition of
+speech. He believes that the "rhythms and cadences of oratory are
+derived from previously developed musical powers"--a conclusion "exactly
+opposite" to that arrived at by Mr. Spencer.[12] The emotional
+susceptibility to music, and the delicate perceptions needed for the
+higher branches of art, were apparently the work of natural and sexual
+selection in the long past. Civilization, with its leisure and wealth
+and accumulated knowledge, perfects human faculties by artificial
+cultivation, develops and combines means of enjoyment, and discovers
+unsuspected sources of interest and pleasure. The sense of harmony,
+modern as it seems to be, must have been a latent and indirect
+consequence of the development of the sense of hearing and of melody.
+Use, at least, could never have called it into existence. Nature favours
+and develops enjoyments to a certain extent, for they subserve
+self-preservation and sexual and social preference in innumerable ways.
+But modern aesthetic advance seems to be almost entirely due to the
+culture of latent abilities, the formation of complex associations, the
+selection and encouragement of talent, and the wide diffusion and
+imitation of the accumulated products of the well-cultivated genius of
+favourably varying individuals. The fact that uneducated persons do not
+enjoy the higher tastes, and the rapidity with which such tastes are
+acquired or professed, ought to be sufficient proof that modern culture
+is brought about by far swifter and more potent influences than
+use-inheritance. Neither would this hypothetical factor of evolution
+materially aid in explaining the many other rapid changes of habit
+brought about by education, custom, and the changed conditions of
+civilization generally. Powerful tastes--as is incontestably shown in
+the cases of alcohol and tobacco--lie latent for ages, and suddenly
+become manifest when suitable conditions arise. Every discovery, and
+each step in social and moral evolution, produces its wide-spreading
+train of consequences. I see no reason why use-inheritance need be
+credited with any share in the cumulative results of the invention of
+printing and the steam-engine and gunpowder, or of freedom and security
+under representative government, or of science and art and the partial
+emancipation of the mind of man from superstition, or of the innumerable
+other improvements or changes that take place under modern civilization.
+
+Mr. Spencer suggests an inquiry whether the greater powers possessed by
+eminent musicians were not mainly due to the inherited effect of the
+musical practice of their fathers (p. 19). But these great musicians
+inherited far more than their parents possessed. The excess of their
+powers beyond their parents' must surely be attributed to spontaneous
+variation; and who shall say that the rest was in any way due to
+use-inheritance? If, too, the superiority of geniuses proves
+use-inheritance, why should not the inferiority of the sons of geniuses
+prove the existence of a tendency which is the exact opposite of
+use-inheritance? But nobody collects facts concerning the degenerate
+branches of musical families. Only the favourably varying branches are
+noticed, and a general impression of rapid evolution of talent is thus
+produced. Such cases might be explained, too, by the facts that musical
+faculty is strong in both sexes, that musical families associate
+together, and that the more gifted members may intermarry. Great
+musicians are often astonishingly precocious. Meyerbeer "played
+brilliantly" at the age of six. Mozart played beautifully at four. Are
+we to suppose that the effect of the _adult_ practice of parents was
+inherited at this early age? If use-inheritance was not necessary in the
+case of Handel, whose father was a surgeon, why is it needed to account
+for Bach?
+
+
+LACK OF EVIDENCE.
+
+The "direct proofs" of use-inheritance are not as plentiful as might be
+desired, it appears (pp. 24-28). This acknowledged "lack of recognized
+evidence" is indeed the weakest feature in the case, though Mr. Spencer
+would fain attribute this lack of direct proof to insufficient
+investigation and to the inconspicuous nature of the inheritance of the
+modification. But there is an almost endless abundance of conspicuous
+examples of the effects of use and disuse in the individual. How is it
+that the subsequent inheritance of these effects has not been more
+satisfactorily observed and investigated? Horse-breeders and others
+could profit by such a tendency, and one cannot help suspecting that the
+reason they ignore it must be its practical inefficacy, arising probably
+from its weakness, its obscurity and uncertainty or its non-existence.
+
+
+INHERITED EPILEPSY IN GUINEA-PIGS.
+
+Brown-Sequard's discovery that an epileptic tendency artificially
+produced by mutilating the nervous system of a guinea-pig is
+occasionally inherited may be a fact of "considerable weight," or on the
+other hand it may be entirely irrelevant. Cases of this kind strike one
+as peculiar exceptions rather than as examples of a general rule or law.
+They seem to show that certain morbid conditions may occasionally affect
+both the individual and the reproductive elements or transmissible type
+in a similar manner; but then we also know that such prompt and complete
+transmission of an artificial modification is widely different from the
+usual rule. Exceptional cases require exceptional explanations, and are
+scarcely good examples of the effect of a general tendency which in
+almost all other cases is so inconspicuous in its immediate effects.
+Further remarks on this inherited epilepsy can be most conveniently
+introduced later on in connection with Darwin's explanation of the
+inherited mutilation which it usually accompanies, but which Mr. Spencer
+does not mention.
+
+
+INHERITED INSANITY AND NERVOUS DISORDERS.
+
+Mr. Spencer infers that, because insanity is usually hereditary, and
+insanity can be artificially produced by various excesses, therefore
+this artificially-produced insanity must also be hereditary (p. 28).
+Direct evidence of this conclusion would be better than a mere inference
+which may beg the very question at issue. That the liability to insanity
+commonly runs in families is no proof that strictly non-inherited
+insanity will subsequently become hereditary. I think that theories
+should be based on facts rather than facts on theories, especially when
+those facts are to be the basis or proof of a further theory.
+
+Mr. Spencer also points out that he finds among physicians "the belief
+that nervous disorders of a less severe kind are inheritable"--a general
+belief which does not necessarily include the transmission of purely
+artificially-produced disorders, and so misses the point which is really
+at issue. He proceeds, however, to state more definitely that "men who
+have prostrated their nervous systems by prolonged overwork or in some
+other way, have children more or less prone to nervousness." The
+following observations will, I think, warrant at least a suspension of
+judgment concerning this particular form of use-inheritance.
+
+(1) The nervousness is seen in the _children_ at an early age, although
+the nervous prostration from which it is supposed to be derived
+obviously occurs in the parent at a much later period of life. This
+change in time is contrary to the rule of inheritance at corresponding
+periods; and, together with the unusual promptness and comparative
+completeness of the inheritance, it may indicate a special injury or
+deterioration of the reproductive elements rather than true inheritance.
+The healthy brain of early life has failed to transmit its robust
+condition. Is use-inheritance, then, only effective for evil? Does it
+only transfer the newly-acquired weakness, and not the previous
+long-continued vigour?
+
+(2) Members of nervous families would be liable to suffer from nervous
+prostration, and by the ordinary law of heredity alone would transmit
+nervousness to their children.
+
+(3) The shattered nerves or insanity resulting from alcoholic and other
+excesses, or from overwork or trouble, are evidently signs of a grave
+constitutional injury which may react upon the reproductive elements
+nourished and developed in that ruined constitution. The deterioration
+in parent and child may often display itself in the same organs--those
+probably which are hereditarily weakest. Acquired diseases or disorders
+thus appear to be transmitted, when all that was conveyed to the
+offspring was the exciting cause of a lowered vitality or disordered
+action, together with the ancestral liability to such diseases under
+such conditions.
+
+(4) Francis Galton says that "it is hard to find evidence of the power
+of the personal structure to react upon the sexual elements, that is not
+open to serious objection." Some of the cases of apparent inheritance he
+regards as coincidence of effect. Thus "the fact that a drunkard will
+often have imbecile children, although his offspring previous to his
+taking to drink were healthy," is an "instance of simultaneous action,"
+and not of true inheritance. "The alcohol pervades his tissues, and, of
+course, affects the germinal matter in the sexual elements as much as it
+does that in his own structural cells, which have led to an alteration
+in the quality of his own nerves. Exactly the same must occur in the
+case of many constitutional diseases that have been acquired by
+long-continued irregular habits."[13]
+
+
+INDIVIDUAL AND TRANSMISSIBLE TYPE NOT MODIFIED ALIKE BY THE DIRECT
+EFFECT OF CHANGED HABITS OR CONDITIONS.
+
+Mr. Spencer finds it hard to believe that the modifications conveyed to
+offspring are not identical in tendency with the changes effected in the
+parent by altered use or habit (pp. 23-25, 34). But it is perfectly
+certain that the two sets of effects do not necessarily correspond. The
+effect of changed habits or conditions on the individual is often very
+far from coinciding with the effects on the reproductive elements or
+the transmissible type. The reproductive system is "extremely
+sensitive" to very slight changes, and is often powerfully affected by
+circumstances which otherwise have little effect on the individual
+(_Origin of Species_, p. 7). Various animals and plants become sterile
+when domesticated or supplied with too much nourishment. The native
+Tasmanians have already become extinct from sterility caused by greatly
+changed diet and habits. If, as Mr. Spencer teaches, continued culture
+and brain-work will in time produce lessened fertility or comparative
+sterility, we may yet have to be careful that intellectual development
+does not become a species of suicide, and that the culture of the race
+does not mean its extinction--or at least the extinction of those most
+susceptible of culture.
+
+The reproductive elements are also disturbed and modified in innumerable
+minor ways. Changed conditions or habits tend to produce a general
+"plasticity" of type, the "indefinite variability" thus caused being
+apparently irrelevant to the change, if any, in the individual.[14] A
+vast number of variations of structure have certainly arisen
+independently of similar parental modification as the preliminary.
+Whatever first caused these "spontaneous" congenital variations affected
+the reproductive elements quite differently from the individual. "When a
+new peculiarity first appears we can never predict whether it will be
+inherited." Many varieties of plants only keep true from shoots, and not
+from seed, which is by no means acted on in the same way as the
+individual plant. Seeing that such plants have _two_ reproductive
+types, both constant, it is evident that these cannot both be modified
+in the same way as the parent is modified. Many parental modifications
+of structure and habit are certainly not conveyed to neuter ants and
+bees; other modifications, which are not seen in the parents, being
+conveyed instead. Many other circumstances tend to show that the
+individual and the transmissible type are independent of each other so
+far as modifications of parts are concerned.
+
+It may seem natural to expect the transmission of an enlarged muscle or
+a cultivated brain, but, on the other hand, why should it be
+unreasonable to expect that a modification which was non-congenital in
+origin should still remain non-congenital? Why should the
+non-transmission of that which was not transmitted be surprising?
+
+Mr. Spencer thinks that the non-transmission of acquired modifications
+is incongruous with the great fact of atavism. But the great law of the
+inheritance of that which is a development of the transmissible type
+does not necessarily imply the inheritance of modifications acquired by
+the individual. Because English children may inherit blue eyes and
+flaxen hair from their Anglo-Saxon ancestors, it by no means follows
+that an Englishman must inherit his father's sunburnt complexion or
+smooth-shaven face. Of course atavism ultimately adopts many instances
+of revolt against its sway. But to assume that these changes of type
+_follow_ the personal change rather than cause it, is to assume the
+whole question at issue. That like begets like is true as a broad
+principle, but it has many exceptions, and the non-heredity of acquired
+characters may be one of them.
+
+
+FOOTNOTES:
+
+[2] _Principles of Biology_, Sec. 166, footnote. The English jaws are
+somewhat lighter than the Australian jaws, though I could not undertake
+to affirm that they are really shorter and smaller. In the typical
+skulls depicted on p. 68 of the official guide to the mammalian
+galleries at South Kensington, the typical Caucasian jaw is very much
+larger than the Tasmanian jaw, although the repulsively obtrusive teeth
+of the latter convey the contrary idea to the imagination. Mr. Spencer's
+assumption that the ancient Britons had large jaws appears to me
+erroneous. (See Professor Rolleston's _Scientific Papers and Addresses_,
+i. p. 250.)
+
+[3] Romanes, Galton, and Weismann have made great use of this principle
+in explaining the diminution of disused organs. Weismann has given it
+the name of _Panmixia_,--_all_ individuals being equally free to survive
+and commingle their variations, and not merely selected or favoured
+individuals. See his _Essays on Heredity_, &c., p. 90 (Clarendon Press).
+
+[4] Inclusive in each case of fixed strengthening wire weighing about a
+sixteenth of an ounce or less.
+
+[5] References of course are to _Factors of Organic Evolution_.
+
+[6] P. 13; and _Nineteenth Century_, February, 1888, p. 211.
+
+[7] Tomes's _Dental Surgery_, pp. 273-275. Tomes observes that it is as
+yet uncertain in what way civilization predisposes to caries. But he
+shows that caries is caused by the lime salts in the teeth being
+attacked by _acids_ from decomposing food in crevices, from artificial
+drink such as cyder, from sugar, from medicine, and from vitiated
+secretions of the mouth. It is evident that in civilized races natural
+selection cannot so rigorously insist on sound teeth, sound
+constitutions, and _protective alkaline_ saliva. The reaction of the
+civilized mouth is often acid, especially when the system is disordered
+by dyspepsia or other diseases or forms of ill-health common under
+civilization. The main supply of saliva, which is poured from the cheeks
+opposite the upper molars, is often acid when in small quantities. But
+the submaxillary and sub-lingual saliva poured out at the foot of the
+lower incisors and held in the front part of the jaw as in a spoon,
+"differs from parotid saliva in being more alkaline" (Foster's _Text
+Book of Physiology_, p. 238; Tomes, pp. 284, 685). One observer says
+that the reaction near the lower incisors is "never acid." Hence (I
+conclude) the remarkable immunity of the lower incisors and canines from
+decay, an immunity which extends backwards in a lessening degree to the
+first and second bicuspids. The close packing of the lower incisors may
+assist by preventing the retention of decaying fragments of food. Sexual
+selection may promote caries by favouring white teeth, which are more
+prone to decay than yellow ones. Acid vitiation of the mucus might
+account both for caries and (possibly) for the strange infertility of
+some inferior races under civilization.
+
+[8] _Origin of Species_, pp. 198-9; _Variation of Animals and Plants
+under Domestication_, vol. ii. p. 328 footnote, also p. 206.
+
+[9] Mr. Spencer weakly argues that an advantageous attribute (such as
+swiftness, keen sight, courage, sagacity, strength, &c.) cannot be
+increased by natural selection unless it is "of greater importance, for
+the time being, than most of the other attributes"; and that natural
+selection cannot develop any one superiority when animals are equally
+preserved by "other superiorities." But as natural selection will
+simultaneously eliminate tendencies to slowness, blindness, deafness,
+stupidity, &c., it _must_ favour and improve many points simultaneously,
+although no one of them may be of greater importance than the rest. Of
+course the more complicated the evolution the slower it will be; but
+time is plentiful, and the amount of elimination is correspondingly
+vast.
+
+[10] I venture to coin this concise term to signify _the direct
+inheritance of the effects of use and disuse in kind_. Having a name for
+a thing is highly convenient; it facilitates clearness and accuracy in
+reasoning, and in this particular inquiry it may save some confusion of
+thought from double or incomplete meanings in the shortened phrases
+which would otherwise have to be employed to indicate this great but
+nameless factor of evolution.
+
+[11] _Origin of Species_, pp. 230-232; Bates's _Naturalist on the
+Amazons_. Darwin is "surprised that no one has hitherto advanced the
+demonstrative case of neuter insects, against the well-known doctrine of
+inherited habit, as advanced by Lamarck." As he justly observes, "it
+proves that with animals, as with plants, any amount of modification may
+be effected by the accumulation of numerous, slight, spontaneous
+variations, which are in any way profitable, without exercise or habit
+having been brought into play. For peculiar habits confined to the
+workers or sterile females, however long they might be followed, could
+not possibly affect the males and fertile females, which alone leave any
+descendants." Some slight modification of these remarks, however, may
+possibly be needed to meet the case of "factitious queens," who
+(probably through eating particles of the royal food) become capable of
+producing a few male eggs.
+
+[12] _Descent of Man_, pp. 573, 572, and footnote.
+
+[13] _Contemporary Review_, December, 1875, p. 92.
+
+[14] See _Origin of Species_, pp. 5-8. "Changed conditions induce an
+almost indefinite amount of fluctuating variability, by which the whole
+organization is rendered in some degree plastic" (_Descent of Man_, p.
+30). It also appears that "the nature of the conditions is of
+subordinate importance in comparison with the nature of the organism in
+determining each particular form of variation;--perhaps of not more
+importance than the nature of the spark, by which a mass of combustible
+matter is ignited, has in determining the nature of the flames" (_Origin
+of Species_, p. 8).
+
+
+
+
+DARWIN'S EXAMPLES.
+
+
+The most formidable cases brought forward by Mr. Spencer are from
+Darwin. I shall endeavour to show, however, that Darwin was probably
+wrong in retaining the older explanation of these facts, and that the
+remains of the Lamarckian theory of use-inheritance need not any longer
+encumber the great explanation which has superseded that fallacious and
+unproven theory and has rendered it totally unnecessary. Meanwhile I
+think it is an excellent sign that Mr. Spencer has to complain that
+"Nowadays most naturalists are more Darwinian than Mr. Darwin
+himself"--inasmuch as they are inclined to say that there is "no proof"
+that the effects of use and disuse are inherited. Other excellent signs
+are the recent issue of a translation of Weismann's important essays on
+this and kindred subjects,[15] the strong support given to his views by
+Wallace in his _Darwinism_, and their adoption by Ray Lankester in his
+article on Zoology in the latest edition of the _Encyclopaedia
+Britannica_. So sound and cautious an investigator as Francis Galton had
+also in 1875 concluded that "acquired modifications are barely, if at
+all, _inherited_, in the correct sense of that word."
+
+Darwin's belief in the inheritance of acquired characters was more or
+less hereditary in the family. His grandfather, Erasmus Darwin,
+anticipated Lamarck's views in his _Zoonomia_, which Darwin at one time
+"greatly admired." His father was "convinced" of the "inherited evil
+effects of alcohol," and to this extent at least he strongly impressed
+the belief in the inheritance of acquired characters upon his
+children's minds.[16] Darwin must also have been imbued with Lamarckian
+ideas from other sources, although Dr. Grant's enthusiastic advocacy
+entirely failed to convert him to a belief in evolution.[17]
+"Nevertheless," he says, "it is probable that the hearing rather early
+in life such views maintained and praised may have favoured my upholding
+them under a different form in my _Origin of Species_"--a remark which
+refers to Lamarck's views on the general doctrine of evolution, but
+might also prove equally true if applied to Darwin's partial retention
+of the Lamarckian explanation of that evolution. Professor Huxley has
+pointed out that in Darwin's earlier sketch of his theory of evolution
+(1844) he attached more weight to the inheritance of acquired habits
+than he does in his _Origin of Species_ published fifteen years
+later.[18] He appears to have acquired the belief in early life without
+first questioning and rigorously testing it as he would have done had it
+originated with himself. In later life it appeared to assist his theory
+of evolution in minor points, and in particular it appeared absolutely
+indispensable to him as the _only_ explanation of the diminution of
+disused parts in cases where, as in domestic animals, economy of growth
+seemed to be practically powerless. He failed to adequately notice the
+effect of panmixia, or the withdrawal of selection, in causing or
+allowing degeneracy and dwindling under disuse; and he hardly attached
+sufficient importance to the fact that rudimentary organs and other
+supposed effects of use or disuse are quite as marked features in
+neuter insects which cannot transmit the effects of use and disuse as
+they are in the higher animals.
+
+
+REDUCED WINGS OF BIRDS OF OCEANIC ISLANDS.
+
+Darwin himself has pointed out that the rudimentary wings of island
+beetles, at first thought to be due to disuse, are mainly brought about
+by natural selection--the best-winged beetles being most liable to be
+blown out to sea. But he says that in birds of the oceanic islands "not
+persecuted by any enemies, the reduction of their wings has probably
+been caused by disuse." This explanation may be as fallacious as it is
+acknowledged to have been in the case of the island beetles. According
+to Darwin's own views, natural selection _must_ at least have played an
+important part in reducing the wings; for he holds that "natural
+selection is continually trying to economize every part of the
+organization." He says: "If under changed conditions of life a
+structure, before useful, becomes less useful, its diminution will be
+favoured, for it will profit the individual not to have its nutriment
+wasted in building up an useless structure.... Thus, as I believe,
+natural selection will tend in the long run to reduce any part of the
+organization, as soon as it becomes, through changed habits,
+superfluous."[19] If, as Darwin powerfully urges (and he here ignores
+his usual explanation), ostriches' wings are insufficient for flight in
+consequence of the economy enforced by natural selection,[20] why may
+not the reduced wings of the dodo, or the penguin, or the apteryx, or of
+the Cursores generally, be wholly attributed to natural selection in
+favour of economy of material and adaptation of parts to changed
+conditions? The great principle of economy is continually at work
+shaping organisms, as sculptors shape statues, by removing the
+superfluous parts; and a mere glance at the forms of animals in general
+will show that it is well-nigh as dominant and universal a principle as
+is that of the positive development of useful parts. Other causes,
+moreover besides actual economy, would favour shorter and more
+convenient wings on oceanic islands. In the first place, birds that were
+somewhat weak on the wing would be most likely to settle on an island
+and stay there. Shortened wings would then become advantageous because
+they would restrain fatal migratory tendencies or useless and perilous
+flights in which the birds that flew furthest would be most often
+carried away by storms and adverse winds. Reduced wings would keep the
+birds near the shelter and the food afforded by the island and its
+neighbourhood, and in some cases would become adapted to act as fins or
+flappers for swimming under water in pursuit of fish.
+
+The reduced size of the wings of these island birds is paralleled by the
+remarkable thinness, &c., of the shell of the "gigantic land-tortoise"
+of the Galapagos Islands. The changes seen in the carapace can hardly
+have been brought about by the inherited effects of special disuse. Why
+then should not the reduction of equally useless, more wasteful, and
+perhaps positively dangerous wings be also due to an economy which has
+become advantageous to bird and reptile alike through the absence of the
+mammalian rivals whose places they are evidently being modified to fill?
+The _complete_ loss of the wings in neuter ants and termites can
+scarcely be due to the inherited effects of disuse; and as natural
+selection has abolished these wings in spite of the opposition of
+use-inheritance, it must clearly be fully competent to reduce wings
+without its aid. In considering the rudimentary wings of the apteryx,
+or of the moa, emu, ostrich, &c., we must not forget the frequent or
+occasional occurrence of hard seasons, and times of drought and famine,
+when Nature eliminates redundant, wasteful, and ill-adapted organisms in
+so severe and wholesale a fashion. Where enemies are absent there would
+be unrestrained multiplication, and this would greatly increase the
+severity of the competition for food, and so hasten the elimination of
+disused and useless parts.
+
+
+DROOPING EARS AND DETERIORATED INSTINCTS.
+
+Mr. Galton has pointed out that existing races and existing organs are
+only kept at their present high pitch of organic excellence by the
+stringent and incessant action of natural or artificial selection; and
+the simple relaxation or withdrawal of such selective influences will
+almost necessarily result in a certain amount of deterioration,
+independently even of the principle of economy.[21] I think that this
+cessation of a previous selective process will account for the
+drooping--but _not diminished_--ears of various domesticated animals
+(human preference and increased weight evidently aiding), and also for
+the inferior instincts seen in them and in artificially-fed caterpillars
+of the silk-moth, which now "often commit the strange mistake of
+devouring the base of the leaf on which they are feeding, and
+consequently fall down." Anyhow, I fail to see that anything is proved
+by this latter case, except that natural instinct may be perverted or
+aborted under unnatural conditions and a changed method of selection
+which abolishes the powerful corrective formerly supplied by natural
+selection.
+
+
+WINGS AND LEGS OF DUCKS AND FOWLS.
+
+The reduced wings and enlarged legs of domesticated ducks and fowls are
+attributed by Darwin and Spencer to the inheritance of the effects of
+use and disuse. But the inference by no means follows. Natural selection
+would usually favour these adaptive changes, and they would also have
+been aided by an artificial selection which is often unconscious or
+indirect. Birds with diminished power of flight would be less difficult
+to keep and manage, and in preserving and multiplying such birds man
+would be unconsciously bringing about structural changes which would
+easily be regarded as effects of use and disuse. "About eighteen
+centuries ago Columella and Varro speak of the necessity of keeping
+ducks in netted enclosures like other wild fowl, so that at this period
+there was danger of their flying away."[22] Is it not probable that the
+best fliers would escape most frequently, or would pine most if kept
+confined? On the other hand, birds with lessened powers of flight would
+not be eliminated as under natural conditions, but would be favoured;
+and natural selection, together with artificial selection of the most
+flourishing birds, would thicken and strengthen the legs to meet
+increased demands upon them.
+
+The diminution of the duck's wing is not great even in the birds that
+"never fly," and from this we must deduct the direct effect of disuse on
+the individual during its lifetime. As Weismann suggests, the
+_inherited_ portion of the change could only be ascertained by comparing
+the bones, &c., of wild and tame ducks _similarly reared_. If individual
+disuse diminished the weight of the duck's wing-bones by 9 per cent.
+there would be nothing left to account for.
+
+I suspect that investigation would reveal anomalies inconsistent with
+the theory of use-inheritance. Thus according to Darwin's tables of
+comparative weights and measurements[23] the leg-bones of the Penguin
+duck have slightly diminished in length, although they have increased 39
+per cent. in weight. Relatively to the weight of the skeleton, the
+leg-bones have shortened in the tame breeds of ducks by over 5 per cent.
+(and in two breeds by over 8 per cent.) although they have increased
+more than 28 per cent. in proportional weight.[24] How can increased use
+simultaneously shorten and thicken these bones? If the relative
+shortening is attributed to a heavier skeleton, then the apparently
+reduced weight of the wing-bones is fully accounted for by the same
+circumstance, and disuse has had no inherited effect.
+
+Another strange circumstance is that the wing-bones have diminished _in
+length only_. The shortening is about 6 per cent. more than in the
+shortened legs, and it amounts to 11 per cent. as compared with the
+weight of the skeleton. Such a shortening should represent a reduction
+of 29 per cent. in weight, whereas the actual reduction in the weight of
+the wing-bones relatively to the weight of the skeleton is only 9 per
+cent. even in the breeds that never fly. Independently of shortening,
+the disused wing-bones have actually thickened or increased in weight.
+In the Aylesbury duck the disproportion caused by these conflicting
+changes is so great that the wing-bones are 47 per cent. heavier than
+they should be if their weight had varied proportionally with their
+length.[25] The reduction in weight on which Darwin relies seems to be
+entirely due to the shortening, and this shortening appears to be
+irrelevant to disuse, since the wings of the Call duck are similarly
+shortened in their proportions by 12 per cent., although this bird
+habitually flies to such an extent that Darwin partly attributes the
+greatly increased weight of its wing-bones to increased use under
+domestication.
+
+We find that _all_ the changes are in the direction of shorter and
+thicker bones--a tendency which must be largely dependent upon the
+suspension of the rigorous elimination which keeps the bones of the
+wild duck _long and light_. The used leg-bones and the disused
+wing-bones have alike been shortened and thickened, though in different
+proportions. Natural or artificial selection might easily thicken legs
+without lengthening them, or shorten wings without eliminating strong
+heavy bones, but it can hardly be contended that use-inheritance has
+acted in such conflicting ways. The thickening of the wing-bones has
+actually more than kept pace with any increase of weight in the
+skeleton, in spite of the effect of individual disuse and of the alleged
+cumulative effect of ancestral disuse for hundreds of generations. The
+case of the duck deserves special attention as a crucial one, if only
+from the fact that in this instance, and in this instance only, has
+Darwin given the weights of the skeletons, thus furnishing the means for
+a closer examination of his details than is usually possible.
+
+If we ignore such factors as selection, panmixia, correlation, and the
+effects of use and disuse during lifetime, and still regard the case of
+the domestic duck as a valid proof of the inheritance of the effects of
+use and disuse, we must also accept it as an equally valid proof that
+the effects of use and disuse are _not_ inherited. Nay, we may even have
+to admit that, in two points out of four, the _inherited_ effect of use
+and disuse on successive generations is exactly opposite to the
+immediate effect on the individual.
+
+Among fowls the wing-bones have lost much in weight but little or
+nothing in length--which is the reverse of what has occurred in ducks,
+although disuse is alleged to be the common cause in both cases. Some of
+the fowls which fly least have their wing-bones as long as ever. In the
+case of the Silk and Frizzled fowls--ancient breeds which "cannot fly at
+all"--and in that of the Cochins, which "can hardly fly up to a low
+perch," Darwin observes "how truly the proportions of an organ may be
+inherited although not fully exercised during many generations."[26] In
+four out of twelve breeds the wing-bones had become slightly heavier
+relatively to the leg-bones. Do not these facts tend to show that the
+changes in fowls' wings are due to fluctuating variability and selective
+influences rather than to a general law whereby the effects of disuse
+are cumulatively inherited?
+
+
+PIGEONS' WINGS.
+
+Concerning pigeons' wings Darwin says: "As fancy pigeons are generally
+confined in aviaries of moderate size, and as even when not confined
+they do not search for their own food, they must during many generations
+have used their wings incomparably less than the wild rock-pigeon ...
+but when we turn to the wings we find what at first appears a wholly
+different and unexpected result."[27] This unexpected increase in the
+spread of the wings from tip to tip is due to the feathers, which have
+lengthened in spite of disuse. Excluding the feathers, the wings were
+shorter in seventeen instances, and longer in eight. But as artificial
+selection has lengthened the wings in some instances, why may it not
+have shortened them in others? Wings with shortened bones would fold up
+more neatly than the long wings of the Carrier pigeon for instance, and
+so might unconsciously be favoured by fanciers. The selection of elegant
+birds with longer necks or bodies would cause a relative reduction in
+the wings--as with the Pouter, where the wings have been greatly
+lengthened but not so much as the body.[28] Slender bodies, too, and the
+lessened divergence of the furculum,[29] would slightly diminish the
+spread of the wings, and so would affect the measurements taken. As the
+wing-bones, moreover, are to some extent correlated with the beak and
+the feet, the artificial selection of shortened beaks might tend to
+shorten the wing as well as the feet. Under these circumstances how can
+we be sure of the actual efficacy of use-inheritance? Surely selection
+is as fully competent to effect slight changes in the direction of
+use-inheritance as it undoubtedly is to effect great changes in direct
+opposition to that alleged factor of evolution.
+
+
+SHORTENED BREAST-BONE IN PIGEONS.
+
+The shortening of the sternum in pigeons is attributed to disuse of the
+flight muscles attached to it. The bone is only shortened by a third of
+an inch, but this represents a very remarkable reduction in proportional
+length, which Darwin estimates at from one-seventh to one-eighth, or
+over 13 per cent. This marked reduction, too, quite unlike the slight
+reduction of the wing-bones to which the other ends of the muscles are
+attached, was universal in the eleven specimens measured by Darwin; and
+the bone, though acknowledged to have been modified by artificial
+selection in some breeds, is not so open to observation as wings or
+legs. Even, however, if this relative shortening of the sternum remained
+otherwise inexplicable, it might still be as irrelevant to use and
+disuse as is the fact that "many breeds" of fancy pigeons have lost a
+rib, having only seven where the ancestral rock-pigeon has eight.[30]
+But the excessive reduction in the sternum is far from being
+inexplicable. In the first place Darwin has somewhat over-estimated it.
+Instead of comparing the deficiency of length with the increased length
+which _should_ have been acquired (since the pigeons have increased in
+average size) he compares it with the length of the breast-bone in the
+rock-pigeon.[31] By this method if a pigeon had doubled in dimensions
+while its breast-bone remained unaltered, the reduction would be put
+down as 100 per cent., whereas obviously the true reduction would be
+one-half, or 50 per cent. of what the bone _should be_. Avoiding this
+error and a minor fallacy besides, a sound estimate reduces the supposed
+reduction of 13 or 14 per cent. to one of 11.7 per cent., which is still
+of course a considerable diminution.
+
+Part of this reduction must be due to the direct effect of disuse during
+the lifetime of the individual. Another and perhaps very considerable
+part of the relative change must be attributed to the lengthening of the
+neck or body by artificial selection, or to other modifications of
+shape and proportion effected directly or indirectly by the same
+cause.[32] The reduction is greatest in the Pouter (18-1/2 per cent.)
+and in the Pied Scanderoon (17-1/2 per cent.). In the former the body
+has been greatly elongated by artificial selection and three or four
+additional vertebrae have been acquired in the hinder part of the
+body.[33] In the latter a long neck increases the length of the bird,
+and so causes, or helps to cause, the relative shortening of the
+breast-bone. In the English Carrier--which experiences the effects of
+disuse, as it is too valuable to be flown--the relative reduction of 11
+per cent. is apparently more than accounted for by the "elongated
+neck." The Dragon also has a long neck. In the Pouter, although the
+breast-bone has been shortened by 18-1/2 per cent. relatively to the
+length of the body, it has _lengthened_ by 20 per cent. relatively to
+the _bulk_ of the body.[34] Darwin forgot to ask whether allowance must
+not be made for a frequent, or perhaps general, elongation of the neck
+and the hinder part of the body, and the relative shortening or the
+throwing forward of the central portion containing the ribs (frequently
+one less in number) and the sternum. The whole body of the pigeon is so
+much under the control of artificial selection, that every precaution
+must be taken to guard against such possible sources of error.[35]
+
+Under domestication there would be a suspension of the previous
+elimination of reduced breast-bones by natural selection (Weismann's
+panmixia), and a diminution of the parts concerned in flying might even
+be favoured, as lessened powers of _continuous_ flight would prevent
+pigeons from straying too far, and would fit them for domestication or
+confinement. Such causes might reduce some of the less observed parts
+affected by flying, while still leaving the wing of full size for
+occasional flight, or to suit the requirements of the pigeon-fanciers. A
+change might thus be commenced like that seen in the rudimentary keel of
+the sternum in the owl-parrot of New Zealand, which has lost the power
+of flight although still retaining fairly-developed wings.
+
+
+SHORTENED FEET IN PIGEONS.
+
+Darwin thinks it highly probable that the short feet of most breeds of
+pigeons are due to lessened use, though he owns that the effects of
+correlation with the shortened beak are more plainly shown than the
+effects of disuse.[36] But why need the inherited effects of disuse be
+called in to explain an average reduction of some 5 per cent., when
+Darwin's measurements show that in the breeds where long beaks are
+favoured the principle of correlation between these parts has lengthened
+the foot by 13 per cent. in spite of disuse?
+
+
+SHORTENED LEGS OF RABBITS.
+
+In the case of the domestic rabbit Darwin notices that the bones of the
+legs have (relatively) become shorter by an inch and a half. But as the
+leg-bones have _not_ diminished in relative weight,[37] they must
+clearly have grown _thicker_ or denser. If disuse has shortened them, as
+Darwin supposes, why has it also thickened them? The ears and the tail
+have been lengthened in spite of disuse. Why then may not the ungainly
+hind-legs have been shortened by human preference independently of the
+inherited effects of disuse? By relying on apparently favourable
+instances and neglecting the others it would be easy to arrive at all
+manner of unsound conclusions. We might thus become convinced that
+vessels tend to sail northwards, or that a pendulum oscillates more
+often in one direction than in the other. It must not be forgotten that
+it would be easy to cite an enormous number of cases which are in direct
+conflict with the supposed law of use-inheritance.
+
+
+BLIND CAVE-ANIMALS.
+
+Weak or defective eyesight is by no means rare as a spontaneous
+variation in animals, "the great French veterinary Huzard going so far
+as to say that a blind race [of horses] could soon be formed." Natural
+selection evolves blind races whenever eyes are useless or
+disadvantageous, as with parasites. This may apparently be done
+independently of the effects of disuse, for certain neuter ants have
+eyes which are reduced to a more or less rudimentary condition, and
+neuter termites are blind as well as wingless. In one species of ant
+(_Eciton vastator_) the sockets have disappeared as well as the eyes. In
+deep caves not only would natural selection cease to maintain good
+eyesight but it would persistently favour blindness--or the entire
+removal of the eye when greatly exposed, as in the cave-crab--and as Dr.
+Ray Lankester has indicated,[38] there would have been a previous
+selection of animals which through spontaneous weakness, sensitiveness,
+or other affection of the eye found refuge and preservation in the cave,
+and a subsequent selection of the descendants whose fitness for relative
+darkness led them deeper into the cave or prevented them from straying
+back to the light with its various dangers and severer competition.
+Panmixia, however, as Weismann has shown, would probably be the most
+important factor in causing blindness.
+
+
+INHERITED HABITS.
+
+Darwin says: "A horse is trained to certain paces, and the colt inherits
+similar consensual movements."[39] But selection of the constitutional
+tendency to these paces, and imitation of the mother by the colt, may
+have been the real causes. The evidence, to be satisfactory, should show
+that such influences were excluded. Men acquire proficiency in swimming,
+waltzing, walking, smoking, languages, handicrafts, religious beliefs,
+&c., but the children only appear to inherit the innate abilities or
+constitutional proclivities of their parents. Even the songs of birds,
+including their call-notes, are no more inherited than is language by
+man (_Descent of Man_, p. 86). They are learned from the parent.
+Nestlings which acquire the song of a distinct species, "teach and
+transmit their new song to their offspring." If use-inheritance has not
+fixed the song of birds, why should we suppose that in a single
+generation it has transmitted a newly-taught method of walking or
+trotting?
+
+It is alleged that dogs inherit the intelligence acquired by association
+with man, and that retrievers inherit the effects of their
+training.[40] But selection and imitation are so potent that the
+additional hypothesis of use-inheritance seems perfectly superfluous.
+Where intelligence is not highly valued and carefully promoted by
+selection, the intelligence derivable from association with man does
+_not_ appear to be inherited. Lap-dogs, for instance, are often
+remarkably stupid.
+
+Darwin also instances the inheritance of dexterity in seal-catching as a
+case of use-inheritance.[41] But this is amply explained by the ordinary
+law of heredity. All that is needed is that the son shall inherit the
+suitable faculties which the father inherited before him.
+
+
+TAMENESS OF RABBITS.
+
+Darwin holds that in some cases selection alone has modified the
+instincts and dispositions of domesticated animals, but that in most
+cases selection and the inheritance of acquired habits have concurred in
+effecting the change. "On the other hand," he says, "habit alone in some
+cases has sufficed; hardly any animal is more difficult to tame than the
+young of the wild rabbit; scarcely any animal is tamer than the young of
+the tame rabbit; but I can hardly suppose that domestic rabbits have
+often been selected for tameness alone; so that we must attribute at
+least the greater part of the inherited change from extreme wildness to
+extreme tameness to habit and long-continued close confinement."[42]
+
+But there are strong, and to me irresistible, arguments to the contrary.
+I think that the following considerations will show that the greater
+part, if not the whole, of the change must be attributed to selection
+rather than to the direct inheritance of acquired habit.
+
+(1) For a period which may cover thousands of generations, there has
+been an entire cessation of the natural selection which maintains the
+wildness (or excessive fear, caution, activity, &c.) so indispensably
+essential for preserving defenceless wild rabbits of all ages from the
+many enemies that prey upon them.
+
+(2) During this same extensive period of time man has usually killed off
+the wildest and bred from the tamest and most manageable. To some extent
+he has done this consciously. "It is very conducive to successful
+breeding to keep only such as are quiet and tractable," says an
+authority on rabbits,[43] and he enjoins the selection of the
+handsomest and _best-tempered_ does to serve as breeders. To a still
+greater extent man has favoured tameness unconsciously and indirectly.
+He has systematically selected the largest and most prolific animals,
+and has thus doubled the size and the fertility of the domestic rabbit.
+In consciously selecting the largest and most flourishing individuals
+and the best and most prolific mothers, he _must_ have unconsciously
+selected those rabbits whose relative _tameness_ or placidity of
+disposition rendered it possible for them to flourish and to produce and
+rear large and thriving families, instead of fretting and pining as the
+wilder captives would do. When we consider how exceedingly delicate and
+easily disturbed yet all-important a function is that of maternity in
+the continually breeding rabbit, we see that the tamest and the least
+terrified would be the most successful mothers, and so would continually
+be selected, although man cared nothing for the tameness in itself. The
+tamest mothers would also be less liable to neglect or devour their
+offspring, as rabbits commonly do when their young are handled too soon,
+or even when merely frightened by mice, &c., or disturbed by changed
+surroundings.
+
+(3) We must remember the extraordinary fecundity of the rabbit and the
+excessive amount of elimination that consequently takes place either
+naturally or artificially. Where nature preserved only the wildest, man
+has preserved the tamest. If there is any truth in the Darwinian theory,
+this thorough and long-continued reversal of the selective process
+_must_ have had a powerful effect. Why should it not be amply sufficient
+to account for the tameness and mental degeneracy of the rabbit without
+the aid of a factor which can readily be shown to be far weaker in its
+normal action than either natural or artificial selection? Why may not
+the tameness of the rabbit be transferred to the group of cases in
+which Darwin holds that "habit has done nothing," and selection has done
+all?
+
+(4) If use-inheritance has tamed the rabbit, why are the bucks still so
+mischievous and unruly? Why is the Angora breed the only one in which
+the males show no desire to destroy the young? Why, too, should
+use-inheritance be so much more powerful in the rabbit than with other
+animals which are far more easily tamed in the first instance? Wild
+young rabbits when domesticated "remain unconquerably wild," and,
+although they may be kept alive, they pine and "rarely come to any
+good." Yet the animal which _acquires_ least tameness--or apparently,
+indeed, none at all--inherits most! It appears, in fact, to inherit that
+which it cannot acquire--a circumstance which indicates the selection of
+spontaneous variations rather than the inheritance of changed habits.
+Such variations occasionally occur in animals in a marked degree. Of a
+litter of wolf-cubs, all brought up in the same way, "one became tame
+and gentle like a dog, while the others preserved their natural
+savagery." Is it not probable that permanent domestication was rendered
+possible by the inevitable selection of spontaneous variations in this
+direction? The _excessive_ tameness, too, of the young rabbit, while
+easily explicable as a result of unconscious selection, is not easily
+explained as a result of acquired habit. No particular care is taken to
+tame or teach or domesticate rabbits. They are bred for food, or for
+profit or appearance, and they are left to themselves most of their
+time. As Sir J. Sebright notices with some surprise, the domestic rabbit
+"is not often visited, and seldom handled, and yet it is always tame."
+
+
+MODIFICATIONS OBVIOUSLY ATTRIBUTABLE TO SELECTION.
+
+Innumerable modifications in accordance with altered use or disuse, such
+as the enlarged udders of cows and goats, and the diminished lungs and
+livers in highly bred animals that take little exercise, can be readily
+and fully explained as depending on selection. As the fittest for the
+natural or artificial requirements will be favoured, natural or
+artificial selection may easily enlarge organs that are increasingly
+used and economize in those that are less needed. I therefore see no
+necessity whatever for calling in the aid of use-inheritance as Darwin
+does, to account for enlarged udders, or diminished lungs, or the thick
+arms and thin legs of canoe Indians, or the enlarged chests of
+mountaineers, or the diminished eyes of moles, or the lost feet of
+certain beetles, or the reduced wings of logger-headed ducks, or the
+prehensile tails of monkeys, or the displaced eyes of soles, or the
+altered number of teeth in plaice, or the increased fertility of
+domesticated animals, or the shortened legs and snouts of pigs, or the
+shortened intestines of tame rabbits, or the lengthened intestines of
+domestic cats, &c.[44] Changed habits and the requisite change of
+structure will usually be favoured by natural selection; for habit, as
+Darwin says, "almost implies that some benefit great or small is thus
+derived."
+
+
+SIMILAR EFFECTS OF NATURAL SELECTION AND USE-INHERITANCE.
+
+Here we perceive a difficulty which will equally trouble those who
+affirm use-inheritance and those who deny. Broadly speaking, the
+adaptive effects ascribed to use-inheritance coincide with the effects
+of natural selection. The individual adaptability (as shown in the
+thickening of skin, fur, muscle, &c., under the stimulus of friction,
+cold, use, &c.) is identical in kind and direction with the racial
+adaptability under natural selection. Consequently the alleged
+inheritance of the advantageous effects of use and disuse cannot readily
+be distinguished from the similarly beneficial effects of natural
+selection. The indisputable fact that natural selection imitates or
+simulates the beneficial effects ascribed to use-inheritance may be the
+chief source and explanation of a belief which may prove to be
+thoroughly fallacious. A similar simulation of course occurs under
+domestication, where natural selection is partly replaced by artificial
+selection of the best adapted and therefore most flourishing animals,
+while in disused parts panmixia or the comparative cessation of
+selection will aid or replace "economy of growth" in causing
+diminution.[45]
+
+
+INFERIORITY OF SENSES IN EUROPEANS.
+
+"The inferiority of Europeans, in comparison with savages, in eyesight
+and in the other senses," is attributed to "the accumulated and
+transmitted effect of lessened use during many generations."[46] But why
+may we not attribute it to the slackened and diverted action of the
+natural selection which keeps the senses so keen in some savage races?
+
+
+SHORT-SIGHT IN WATCHMAKERS AND ENGRAVERS.
+
+Darwin notices that watchmakers and engravers are liable to be
+short-sighted, and that short-sight and long-sight certainly tend to be
+inherited.[47] But we must be careful not to beg the question at issue
+by assuming that the frequent heredity of short sight necessarily covers
+the heredity of artificially-produced short-sight. Elsewhere, however,
+Darwin states more decisively that "there is ground for believing that
+it may often originate in causes acting on the individual affected, and
+may thence-forward become transmissible."[48] This impression may arise
+(1) from the facts of ordinary heredity--the ancestral liability being
+excited in father and son by similar artificial habits, such as reading,
+and viewing objects closely as among watchmakers and engravers--or by
+constitutional deterioration from indoor life, &c., acting upon a
+constitutional liability of the eye to the "something like inflammation
+of the coats, under which they yield" and so cause shortness of sight
+by altering the spherical shape of the eye-ball. (2) Panmixia, or the
+suspension of natural selection, together with altered habits, will
+account for an increase of short-sight among the population generally.
+(3) Long-sighted people could not work at watchmaking and engraving so
+comfortably and advantageously as at other occupations, and hence would
+be less likely to take to such callings.
+
+
+LARGER HANDS OF LABOURERS' INFANTS.[49]
+
+These are best explained as the result of natural selection and of the
+diminution of the hand by sexual selection in the gentry. If the larger
+hands of labourers' infants are really due to the inherited effects of
+ancestral use, why does the development occur so early in life, instead
+of only at a corresponding period, as is the rule? During the first few
+years of its life, at least, the labourer's infant does no more work
+than the gentleman's child. Why are not the effects of this disuse
+inherited by the labourer's infant? If the enlargement of the infant's
+hand illustrates the transference of a character gained later in life,
+it is evident that the transference must take place in spite of the
+inherited effects of disuse.
+
+
+THICKENED SOLE IN INFANTS.
+
+Darwin also attributes the thickened sole in infants, "long before
+birth," to "the inherited effects of pressure during a long series of
+generations."[50] But disuse should make the infant's sole _thin_, and
+it is this thinness that should be inherited. If we suppose the
+inheritance of the thickened soles of later life to be transferred to an
+earlier period, we have the anomaly of the inherited effects of disuse
+at that earlier period being overpowered by the untimely inheritance of
+the effects of use at another. On the other hand, it is clear that
+natural selection would favour thickened soles for walking on, and might
+also promote an early development which would ensure their being ready
+in good time for actual use; for variations in the direction of delay
+would be cut off, while variations in the other direction would be
+preserved. Anyhow, the mere transference of a character to an earlier
+period is no proof of use-inheritance. The real question is whether the
+thickened sole was gained by natural selection or by the inherited
+effects of pressure, and the mere transference or hastened appearance of
+the thickening does not in any degree solve this question. It merely
+excludes the effect of disuse during lifetime, and thus presents a
+fallacious appearance of being decisive. The thickened sole of the
+unborn infant, however, like the lanugo or hairy covering, is probably a
+result of the direct inheritance of ancestral stages of evolution, of
+which the embryo presents a condensed epitome. While the relative
+thinness of the infant's sole might be pointed to as the effect of
+_disuse_ during a long series of generations, its thickness is rather an
+illustration of atavism still resisting the effects of long-continued
+disuse. There is nothing to show that the inheritable portion of the
+full original thickness was not gained by natural selection rather than
+by the directly inherited effect of use; and the latter, being
+cumulative and indiscriminative in its action, would apparently have
+made the sole very much thicker and harder than it is. If natural
+selection were not supreme in such cases, how could we account for the
+effects of pressure resulting in hard hoofs in some cases and only soft
+pads in others?
+
+
+A SOURCE OF MENTAL CONFUSION.
+
+Of course in a certain sense this thickening of the sole has resulted
+from use. In one sense or other, most--or perhaps all--of the results of
+natural selection are inherited effects of use or disuse. Natural
+selection preserves that which is of use and which is used, while it
+eliminates that which is useless and is not used. The most confident
+assertions of the effects of use and disuse in modifying the heritable
+type, appear to rest on this indefeasible basis. Darwin's statements
+concerning the effects of use and disuse in evolution can frequently be
+read in two senses. They often command assent as undeniable truisms as
+they stand, but are of course written in another and more debatable
+sense. Thus in the case of the shortened wings and thickened legs of the
+domestic duck, I believe equally with Darwin and Spencer that "no one
+will dispute that they have resulted from the lessened use of the wings
+and the increased use of the legs." "Use" is at bottom the determining
+circumstance in evolution generally. The trunk of the elephant, the fin
+of the fish, the wing of the bird, the cunning hand of man and his
+complicated brain--and, in short, all organs and faculties
+whatsoever--can only have been moulded and developed by use--by
+usefulness and by using--but not necessarily by use-inheritance, not
+necessarily by directly inherited effects of use or disuse of parts in
+the individual. So, too, reduced or rudimentary organs are due to
+disuse, but it by no means follows that the diminution is caused by any
+direct tendency to the inheritance of the effects of disuse in the
+individual. The effects of natural selection are commonly expressible as
+effects of use and disuse, just as adaptation in nature is expressible
+in the language of teleology. But use-inheritance is no more proven by
+one of these necessary coincidences than special design is by the
+other. The inevitable simulation of use-inheritance may be entirely
+deceptive.
+
+Darwin thinks that "there can be no doubt that use in our domestic
+animals has strengthened and enlarged certain parts, and disuse
+diminished them; and that such modifications are inherited." Undoubtedly
+"such" or _similar_ modifications have often been inherited, but how can
+Darwin possibly tell that they are not due to the simulation of
+use-inheritance by natural or artificial selection acting upon general
+variability? Of the inevitability of selection and of its generally
+adaptive tendencies "there can be no doubt," and panmixia would tend to
+reduce disused parts; so that there _must always_ remain grave doubts of
+the alleged inheritance of the similar effects of use and disuse, unless
+we can accomplish the extremely difficult feat of excluding both natural
+and artificial selection as causes of enlargement, and panmixia and
+selection as causes of dwindling.
+
+
+WEAKNESS OF USE-INHERITANCE.
+
+Use-inheritance is normally so weak that it appears to be quite helpless
+when opposed to any other factor of evolution. Natural selection evolves
+and maintains the instincts of ants and termites in spite of
+use-inheritance to a more wonderful degree than it evolves the instincts
+of almost any other animal with the fullest help of use-inheritance. It
+develops seldom-used horns or natural armour just as readily as
+constantly-used hoofs or teeth. Sexual selection evolves elaborate
+structures like the peacock's tail in spite of disuse and natural
+selection combined. Artificial selection appears to enlarge or diminish
+used parts or disused parts with equal facility. The assistance of
+use-inheritance seems to be as unnecessary as its opposition is
+ineffective.
+
+The alleged inheritance of the effects of use and disuse in our domestic
+animals must be very slow and slight.[51] Darwin tells us that "there
+is no good evidence that this ever follows in the course of a single
+generation." "Several generations must be subjected to changed habits
+for any appreciable result."[52] What does this mean? One of two things.
+Either the tendency is very weak, or it is non-existent. If it is so
+weak that we cannot detect its alleged effects till several generations
+have elapsed, during which time the more powerful agency of selection
+has been at work, how are we to distinguish the effects of the minor
+factor from that of the major? Are we to conclude that use-inheritance
+_plus_ selection will modify races, just as Voltaire firmly held that
+incantations, together with sufficient arsenic, would destroy flocks of
+sheep? Is it not a significant fact that the alleged instances of
+use-inheritance so often prove to be self-conflicting in their details?
+
+For satisfactory proof of the prevalence of a law of use-inheritance we
+require normal instances where selection is clearly inadequate to
+produce the change, or where it is scarcely allowed time or opportunity
+to act, as in the immediate offspring of the modified individual. Of the
+first kind of cases there seems to be a plentiful lack. Of the latter
+kind, according to Darwin, there appears to be none--a circumstance
+which contrasts strangely and suspiciously with the many decisive cases
+in which variation from unknown causes has been inherited most
+strikingly in the immediate offspring. It must be expected, indeed, that
+among these innumerable cases some will accidentally mimic the alleged
+effects of use-inheritance.
+
+If Darwin had felt certain that the effects of habit or use tended in
+any marked degree to be conveyed directly and cumulatively to succeeding
+generations, he could hardly have given us such cautious, half-hearted
+encouragement of good habits as the following:--"It is not improbable
+that after long practice virtuous tendencies may be inherited." "Habits,
+moreover followed during many generations probably tend to be
+inherited."[53] This is probable, independently of use-inheritance. The
+"many generations" specified or implied, will allow time for the play of
+selective as well as of cumulatively-educative influences. There must
+apparently be a constitutional or inheritable predisposition or fitness
+for the habits spoken of, which otherwise would scarcely be continued
+for many generations, except by the favourably-varying branches of a
+family: which again is selection rather than use-inheritance.
+
+Where is the necessity for even the remains of the Lamarckian doctrine
+of inherited habit? Seeing how powerful the general principle of
+selection has shown itself in cases where use-inheritance could have
+given no aid or must even have offered its most strenuous opposition,
+why should it not equally be able to develop used organs or repress
+disused organs or faculties without the assistance of a relatively weak
+ally? Selection evolved the remarkable protective coverings of the
+armadillo, turtle, crocodile, porcupine, hedgehog, &c.; it formed alike
+the rose and its thorn, the nut and its shell; it developed the
+peacock's tail and the deer's antlers, the protective mimicry of various
+insects and butterflies, and the wonderful instincts of the white ants;
+it gave the serpent its deadly poison and the violet its grateful odour;
+it painted the gorgeous plumage of the Impeyan pheasant and the
+beautiful colours and decorations of countless birds and insects and
+flowers. These, and a thousand other achievements, it has evidently
+accomplished without the help of use-inheritance. Why should it be
+thought incapable of reducing a pigeon's wing or enlarging a duck's
+leg? Why should it be credited with the help of an officious ally in
+effecting comparatively slight changes, when great and striking
+modifications are effected without any such aid?
+
+
+FOOTNOTES:
+
+[15] Weismann's _Essays on Heredity_, &c. Clarendon Press, 1889.
+
+[16] _Life and Letters_, i. p. 16. Darwin's reverence for his father
+"was boundless and most touching. He would have wished to judge
+everything else in the world dispassionately, but anything his father
+had said was received with almost implicit faith; ... he hoped none of
+his sons would ever believe anything because he said it, unless they
+were themselves convinced of its truth--a feeling in striking contrast
+with his own manner of faith" (_Life and Letters_, i. pp. 10, 11).
+
+[17] _Ibid._, i. p. 38.
+
+[18] _Life and Letters_, ii. p. 14.
+
+[19] _Origin of Species_, pp. 117, 118.
+
+[20] _Ibid._, p. 180.
+
+[21] _Contemporary Review_, December, 1875, pp. 89, 93.
+
+[22] _Variation of Animals and Plants under Domestication_, i. 292.
+
+[23] _Variation of Animals and Plants under Domestication_, i. 299-301.
+
+[24] To keep pace with this lateral increase in weight, the leg-bones
+should have lengthened considerably so that their total deficiency in
+proportional length is 17 per cent.,--a changed proportion which being
+_linear_ is more excessive than the increase of weight by 28 per cent.
+So marked is the effect of the combined thickening and shortening that
+in the Aylesbury breed--which is the most typically representative
+one--the leg-bones have become 70 per cent. heavier than they should be
+if their thickness had continued to be proportional to their length.
+
+[25] This excessive thickening under disuse appears to be due partly to
+a positive lateral enlargement or increase of proportional weight of
+about 7-1/2 per cent., and partly to a shortening of about 15 per cent.
+Carefully calculated, the reduction of the weight of the wing-bones in
+this breed is only 8.3 per cent. relatively to the whole skeleton, or
+only 5 per cent. relatively to the skeleton _minus_ legs and wings. The
+latter method is the more correct, since the excessive weight of the
+leg-bones increases the weight of the skeleton more than the diminished
+weight of the wing-bones reduces it.
+
+[26] _Variation of Animals and Plants under Domestication_, i. 284.
+
+[27] _Variation of Animals and Plants under Domestication_, i. 184, 185.
+
+[28] _Ibid._, i. 144, 145.
+
+[29] _Ibid._, i. 185.
+
+[30] _Variation of Animals and Plants under Domestication_, i. 175.
+
+[31] _Variation of Animals and Plants under Domestication_, i. 184. I
+suspect that Darwin was in poor health when he wrote this page. He nods
+at least four times in it. Twice he speaks of "twelve" breeds where he
+obviously should have said eleven.
+
+[32] If a prominent breast is admired and selected by fanciers, the
+sternum might shorten in assuming a more forward and vertical position.
+If the shortening of the sternum is entirely due to disuse, it seems
+strange that Darwin has not noticed any similar shortening in the
+sternum of the duck. But selection has not tended to make the duck
+elegant, or "pigeon-breasted"; it has enlarged the abdominal sack
+instead, besides allowing the addition of an extra rib in various cases.
+
+[33] _Variation of Animals and Plants under Domestication_, 144, 175.
+
+[34] _Variation of Animals and Plants under Domestication_, i. 179.
+
+[35] In the six largest breeds the shortening of the sternum is nearly
+twice as great as in the three smaller breeds which remain nearest the
+rock-pigeon in size. We can hardly suppose that use-inheritance
+especially affects the eight breeds that have varied most in size. If we
+exclude these, there is only a total shortening of 7 per cent. to be
+accounted for.
+
+[36] _Variation of Animals and Plants under Domestication_, i. 183, 186.
+
+[37] _Variation of Animals and Plants under Domestication_, i. 130, 135;
+ii. 288.
+
+[38] _Encyclopaedia Britannica_, article "Zoology."
+
+[39] _Variation of Animals and Plants under Domestication_, ii. 367.
+
+[40] _Variation of Animals and Plants under Domestication_, ii. 367. Why
+then does the cheetah inherit ancestral habits so inadequately that it
+is useless for the chase unless it has first learned to hunt for itself
+before being captured? (ii. 133).
+
+[41] _Descent of Man_, p. 33.
+
+[42] _Origin of Species_, pp. 210, 211.
+
+[43] E. S. Delamer on _Pigeons and Rabbits_, pp. 132, 103. For other
+points referred to, see pages 133, 102, 100, 95, 131.
+
+[44] _Origin of Species_, pp. 188, 110; _Descent of Man_, pp. 32-35;
+_Variation of Animals and Plants under Domestication_, ii. 289, 293. Use
+or disuse during lifetime of course co-operates, and in some cases, as
+in that of the canoe Indians, may be the principal or even perhaps the
+_sole_ cause of the change.
+
+[45] For the importance of panmixia as invalidating Darwin's strongest
+evidence for use-inheritance--namely, that drawn from the effects of
+disuse in highly-fed domestic animals where there is supposed to be no
+economy of growth--see Professor Romanes on Panmixia, _Nature_, April 3,
+1890.
+
+[46] _Descent of Man_, p. 33.
+
+[47] _Descent of Man_, p. 33.
+
+[48] _Variation of Animals and Plants under Domestication_, i., 453.
+
+[49] _Descent of Man_, p. 33.
+
+[50] _Descent of Man_, p. 33.
+
+[51] Wallace shows that the changes in our domestic animals, if spread
+over the thousands of years since the animals were first tamed, must be
+extremely insignificant in each generation, and he concludes that such
+infinitesimal effects of use and disuse would be swallowed up by the far
+greater effects of variation and selection (_Darwinism_, p. 436).
+Professor Romanes has replied to him in the _Contemporary Review_
+(August 1889), showing that this is no disproof of the existence of the
+minor factor, inasmuch as slight changes in each generation need not
+necessarily be matters of life and death to the individual, although
+their cumulative development by use-inheritance might eventually become
+of much service. But selection would favour spontaneous variations of a
+similarly serviceable character. The slightest tendency to eliminate the
+extreme variations in either direction would proportionally modify the
+average in a breed. Use-inheritance appears to be so relatively weak a
+factor that probably neither proof nor disproof of its existence can
+ever be given, owing to the practical impossibility of disentangling its
+effects (if any) from the effects of admittedly far more powerful
+factors which often act in unsuspected ways. Thus wild ducklings, which
+can easily be reared by themselves, invariably "die off" if reared with
+tame ones (_Variation_, &c., i. 292, ii. 219). They cannot get their
+fair share in the competition for food, and are completely eliminated.
+Professor Romanes fully acknowledges that there is the "gravest possible
+doubt" as to the transmission of the effects of disuse (Letter on
+Panmixia, _Nature_, March 13, 1890).
+
+[52] _Variation of Animals and Plants under Domestication_, ii. 287-289.
+
+[53] _Descent of Man_, pp. 612, 131.
+
+
+
+
+INHERITED INJURIES.
+
+
+INHERITED MUTILATIONS.
+
+The almost universal _non-inheritance_ of mutilations seems to me a far
+more valid argument _against_ a general law of modification-inheritance
+than the few doubtful or abnormal cases of such inheritance can furnish
+in its favour. No inherited effect has been produced by the docking of
+horses' tails for many generations, or by a well-known mutilation which
+has been practised by the Hebrew race from time immemorial. As lost or
+mutilated parts are reproduced in offspring independently of the
+existence of those parts in the parent, there is the less reason to
+suppose that the particular condition of parental parts transmits
+itself, or tends to transmit itself, to the offspring. So unsatisfactory
+is the argument derivable from inherited mutilations that Mr. Spencer
+does not mention them at all, and Darwin has to attribute them to a
+special cause which is independent of any general theory of
+use-inheritance.[54]
+
+Darwin's most striking case--and to my mind the only case of any
+importance--is that of Brown-Sequard's epileptic guinea-pigs, which
+inherited the mutilated condition of parents who had gnawed off their
+own gangrenous toes when anaesthetic through the sciatic nerve having
+been divided.[55] Darwin also mentions a cow that lost a horn by
+accident, followed by suppuration, and subsequently produced three
+calves which had on the same side of the head, instead of a horn, a bony
+lump attached merely to the skin. Such cases may seem to prove that
+mutilation _associated with morbid action_ is occasionally inherited or
+repeated with a promptitude and thoroughness that contrast most
+strikingly with the imperceptible nature of the immediate inheritance of
+the effects of use and disuse; but they by no means prove that
+mutilation in general is inheritable, and they are absolutely no proof
+whatever of a _normal_ and non-pathological tendency to the inheritance
+of acquired characters. Those who accept Darwin's special explanation
+of the supposed inheritance of mutilations, ought to notice that his
+explanation applies equally well under a theory which is strongly
+adverse to use-inheritance--namely, Galton's idea of the sterilization
+and complete "using up" of otherwise reproductive matter in the growth
+and maintenance of the personal structure.
+
+Darwin's explanation of inherited mutilations--which, as he notes, occur
+"especially or perhaps exclusively" when the injury has been followed by
+disease[56]--is that all the representative gemmules which would develop
+or repair or reproduce the injured part are attracted to the diseased
+surface during the reparative process and are there destroyed by the
+morbid action.[57] Hence they cannot reproduce the part in offspring.
+This explanation by no means implies that mutilation would _usually_
+affect the offspring. On the contrary, in all ordinary cases of
+mutilation the purely atavistic elements or gemmules would be set free
+from any modifying influence of the non-existent or mutilated part. The
+gemmules--as in Galton's theory of heredity and with neuter
+insects--might be perfectly independent of pangenesis and the normal
+inheritance of acquired characters. Such self-multiplying gemmules
+without pangenesis would enable us to understand both the excessive
+weakness or non-existence of normal use-inheritance, and the excessive
+strength and abruptness of the effect of their partial destruction under
+special pathological conditions.
+
+The series of epileptic phenomena that can be excited by tickling a
+certain part of the cheek and neck of the adult guinea-pig during the
+growth and rejoining of the ends of the severed nerve, are said to be
+repeated with striking accuracy of detail in the young who inherit
+mutilated toes; but as epilepsy is often due to some _one_ exciting
+cause or morbid condition, the single transmission of a highly morbid
+condition of the system might easily reproduce the whole chain of
+consequences and might also have caused the loss of toes.
+
+The particulars of the guinea-pig cases are very inadequately
+recorded,[58] but the results are so anomalous[59] that Brown-Sequard's
+own conclusion is that the epilepsy and the inherited injuries are
+_not_ directly transmitted, but that "what is transmitted is the morbid
+state of the nervous system." He thinks that the missing toes may
+"possibly" be exceptions to this conclusion, "but the other facts only
+imply the transmission of a morbid state of the sympathetic or sciatic
+nerve or of a part of the medulla oblongata." Until we can tell what is
+transmitted, we are not in a position to determine whether there is any
+true inheritance or only an exaggerated simulation of it under peculiar
+circumstances. When the actual observers believe that the mutilations
+and epilepsy are not the cause of their own repetition, and when these
+observers guard themselves by such phrases as, "if any conclusion can at
+present be drawn from those facts," we who have only incomplete reports
+to guide us may well be excused if we preserve an even more pronounced
+attitude of caution and reserve.[60] The morbid state of the system may
+be wholly due to general injury of the germs rather than to specific
+inheritance.
+
+Weismann suggests that the morbid condition of the nervous system may be
+due to some infection such as might arise from microbes, which find a
+home in the mutilated and disordered nervous system in the parent, and
+subsequently transmit themselves to the offspring through the
+reproductive elements, as the infections of various diseases appear to
+do--the muscardine silkworm disease in particular being known to be
+conveyed to offspring in this manner.
+
+But whether we can discover the true explanation or not, inherited
+mutilations can hardly be accounted for as the result of a general
+tendency to inherit acquired modifications. How could a factor which
+seems to be totally inoperative in cases of ordinary mutilation, and
+only infinitesimally operative in transmitting the normal effects of use
+and disuse, suddenly become so powerful as to completely overthrow
+atavism, and its own tendency to transmit the non-mutilated type of one
+of the parents and of the non-mutilated type presented by the injured
+parent in earlier life? Does not so striking and abrupt an
+intensification of its usually insignificant power demand an explanation
+widely different from that which might account for the extremely slow
+and slight inheritance of the normal effects of use and disuse? Surely
+it would be better to suspend one's judgment as to the true explanation
+of highly exceptional and purely pathological cases rather than resort
+to an hypothesis that creates more difficulties than it solves.
+
+
+THE MOTMOT'S TAIL.
+
+The narrowing of the long central tail feathers of the motmot is
+attributed to the inherited effects of habitual mutilation (_Descent of
+Man_, pp. 384, 603). But in the specimens at South Kensington[61] the
+narrowness extends upwards much beyond the habitually denuded part, and
+the broadened end is the broadest part of the whole feather. If the
+inherited effect of an inch or two of denudation extends from three to
+six inches upwards, why has it not also extended two inches downwards so
+as to narrow the broadened end? The narrowness seems to be a mainly
+relative or negative effect produced by the broadening out of a long
+tapering feather at its end under the influence of sexual selection.
+Several other birds have similarly narrowed or spoon-shaped feathers and
+do not bite them. Is it not more feasible to suppose that this
+attractive peculiarity first suggested its artificial intensification,
+than to suppose that the bird began nibbling without any definite cause?
+Sexual selection would then encourage the habit. Anyhow, it is as
+impossible to show that the mutilation preceded the narrowing as it is
+to show that tonsure preceded baldness.
+
+
+OTHER INHERITED INJURIES MENTIONED BY DARWIN.
+
+Darwin quotes some cases from Dr. Prosper Lucas's "long" but weak and
+unsatisfactory "list of inherited injuries."[62] But Lucas was somewhat
+credulous. One of his cases is that many girls were born in London
+without mammae through the injurious effect of certain corsets on the
+mothers. He also gives a long account of a Jew who could read through
+the thick covers of a book, and whose son inherited this "hyperaesthesia"
+of the sense of sight in a still more remarkable degree (i. 113-119).
+Evidently Lucas's cases cannot be accepted without some amount of
+reserve.
+
+The cases of the three calves which inherited the one-horned condition
+of the cow, the two sons who inherited a father's crooked finger, and
+the two sons who were microphthalmic on the same side as their father
+had lost an eye, may be due to mere coincidence; or an inherited
+constitutional tendency or liability might lead to somewhat similar
+results in parent and offspring[63]--just as the tendency to certain
+fatal diseases or to suicide may produce similar results in father and
+son, although the artificially-produced hanging or apoplexy obviously
+cannot be directly transmitted. That more than one of the offspring was
+affected does not render the chances against coincidence "almost
+infinitely great," as Darwin mistakenly supposes. It "frequently occurs"
+that a man's sons or daughters may _all_ exhibit either a latent or a
+newly-developed congenital peculiarity previously unknown;[64] and the
+coincidence may merely be that one of the parents accidentally suffered
+a similar kind of injury--a kind of coincidence which must of course
+occasionally occur, and which may have been partly caused by a latent
+tendency. The chances against coincidence are indeed great, but the
+cases appear to be correspondingly rare.
+
+Darwin acknowledges that many supposed instances of inherited mutilation
+may be due to coincidence; and there is apparently no more reason for
+attributing inherited scars, &c., to any special form of heredity than
+to the effect of the mother's imagination on the unborn babe--a popular
+but fallacious belief in corroboration of which far more alleged
+instances could be collected than of the inheritance of injuries.
+
+As an instance of the coincidences that occur, I may mention that a
+friend of mine has a daughter who was born with a small hole in one ear,
+just as if it were already pierced for the earring which she has since
+worn in it. I suppose, however, that no one will venture to claim this
+as an instance of the inheritance of a mutilation practised by female
+ancestors, especially as such holes are not altogether unknown or
+inexplicable, though very rarely occurring low down in the lobe of the
+ear.[65]
+
+Many cases are known of the inheritance of mutilations or malformations
+arising congenitally from some abrupt variation in the reproductive
+elements. In such cases as the one-eared rabbits, the two-legged pigs,
+the three-legged dogs, the one-horned stags, hornless bulls, earless
+rabbits, lop-eared rabbits, tailless dogs, &c., if the father or the
+mother or the embryo had suffered from some accident or disease which
+might plausibly have been assigned as the cause of the original
+malformation, these transmitted defects would readily be cited as
+instances of the inheritance of an accidentally-produced modification.
+
+The inheritance of exostoses on horses' legs may be the inheritance of a
+constitutional tendency rather than of the effect of the parents' hard
+travelling. Horses congenitally liable to such formations would transmit
+the liability,[66] and this might readily be mistaken for inheritance of
+the results of the liability. An apparent increase in this liability
+might arise from greater attention being now paid to it, or from
+increased use of harder roads; or a real increase might be due to
+panmixia and some obscure forms of correlation.
+
+
+QUASI-INHERITANCE.
+
+Of course artificially-caused ill-health or weakness in parents will
+tend in a general way to injure the offspring. But deterioration thus
+caused is only a form of quasi-inheritance, as I should prefer to call
+it. Semi-starvation in a new-born babe is _not_ truly inherited from its
+half-starved mother, but is the direct result of insufficient
+nourishment. The general welfare of germs--as of parasites--is
+necessarily bound up with that of the organism which feeds and shelters
+them, but this is not heredity, and is quite irrelevant to the question
+whether particular modifications are transmitted or not.
+
+Another form of quasi-inheritance is seen in the communication of
+certain infections to offspring. Not being transmitted by the action of
+the organism so much as in defiance of it, such diseases are not truly
+hereditary, though for convenience' sake they are usually so described.
+
+A perversion or prevention of true inheritance is also seen in the
+action of alcohol, or excessive overwork, or any other cause which by
+originating morbid conditions in individuals may also injure the
+reproductive elements.
+
+These forms of quasi-inheritance are, of course, highly important so far
+as the improvement of the race is concerned. So, too, is the fact that
+improved or deteriorated habits and thoughts are transmitted by personal
+teaching and influence and are cumulative in their effect. But all this
+must not be confounded with the inheritance of acquired characters.
+Cases of quasi-inheritance may perhaps be most readily distinguished
+from cases of true inheritance by the time test. When a modification
+acquired in adult life is promptly communicated to the child in early
+life or from birth, it may rightly be suspected that the inheritance,
+like that of money or title, is not truly congenital, but is extraneous
+or even anti-congenital in its nature. Judged by such a standard, the
+inherited injuries in Brown-Sequard's guinea-pigs are only exceptional
+cases of quasi-inheritance, and are not necessarily indicative of any
+general rule affecting true inheritance.
+
+
+FOOTNOTES:
+
+[54] A very able anatomist of my acquaintance denies the inheritance of
+mutilations and injuries, although he strongly believes in the
+inheritance of the effects of use and disuse.
+
+[55] _Variation of Animals and Plants under Domestication_, i. 467-469.
+Lost toes were only seen by Dr. Dupuy in three young out of two hundred.
+Obersteiner found that most of the offspring of his epileptic
+guinea-pigs were injuriously affected, being weakly, small, paralysed in
+one or more limbs, and so forth. Only two were epileptic, and both were
+weakly and died early (Weismann's _Essays_, p. 311). A morbid condition
+of the spinal cord might affect the hind limbs especially (as in
+paraplegia) and might occasionally cause loss of toes in the embryo by
+preventing development or by ulceration. Brown-Sequard does not say that
+the defective feet were on the same side as in the parents (_Lancet_,
+Jan., 1875, pp. 7, 8).
+
+[56] _Variation of Animals and Plants under Domestication_, ii. 57.
+
+[57] _Ibid._, ii. 392. Perhaps it might be better to suppose that the
+_best_ gemmules were sacrificed in repairing the injured _nerve_, and
+hence only inferior substitutes were left to take their place, and could
+only imperfectly reproduce the injured part of the nervous system in
+offspring.
+
+[58] Hence perhaps Mr. Spencer's error in representing the epileptic
+liability as permanent and as coming on _after_ healing (_Factors of
+Organic Evolution_, p. 27).
+
+[59] It is not claimed that the imperfect foot was on the same side of
+the body as in the parent, and where parents had lost _all_ the toes of
+a foot, or the whole foot, the few offspring affected usually had lost
+only two toes out of the three, or only a part of one or two or three
+toes. Sometimes the offspring had toes missing on _both_ hind feet,
+although the parent was only affected in _one_. _One_ diseased ear and
+eye in the parent was "generally" or "always" succeeded by _two_ equally
+affected ears and eyes in the offspring (cf. _Pop. Science Monthly_, New
+York, xi. 334). The important law of inheritance at corresponding
+periods was also set aside. Gangrene or inflammation commenced in both
+ears and both eyes soon after birth (pointing possibly to infection of
+some kind); the epileptic period commenced "perhaps two months or more
+after birth," while the loss of toes had occurred before birth. In no
+case, as Weismann points out, is the original mutilation of the nervous
+system ever transmitted. Even where an extirpated ganglion was never
+regenerated in the parent, the offspring always regained the part in an
+apparently perfect condition. On the whole the conflicting results ought
+to be as puzzling to those who may attribute them to a universal
+tendency to inherit the exact condition of parents as they are to those
+who, like myself, are sceptical as to the existence of such a law or
+tendency.
+
+[60] The various results need to be fully and impartially recorded, and
+they should also be well tested and confirmed in proportion as they
+appear improbable and contrary to general experience. Professor Romanes
+has been carrying out the necessary experiments for some time past.
+
+[61] Natural History Museum, central hall, third recess on the left.
+
+[62] _Traite de l'Heredite_, ii. 489; _Variation of Animals and Plants
+under Domestication_, i. 469. If injuries are inherited, why has the
+repeated rupture of the hymen produced no inherited effect?
+
+[63] Compare the three cases of crooked fingers given in _Variation of
+Animals and Plants under Domestication_, ii. 55, 240.
+
+[64] _Ibid._, i. 460. Thus, where two brothers married two sisters all
+the seven children were perfect albinos, although none of the parents or
+their relatives were albinos. In another case the nine children of two
+sound parents were all born blind (ii. 322).
+
+[65] See pp. 179-182, _Evolution and Disease_, by J. Bland Sutton, to
+whom and to our mutual friend Dr. D. Thurston I am indebted for
+information on various points.
+
+[66] _Variation of Animals and Plants under Domestication_, ii. 290; i.
+454.
+
+
+
+
+MISCELLANEOUS CONSIDERATIONS.
+
+
+TRUE RELATION OF PARENTS AND OFFSPRING.
+
+It is difficult to entirely free ourselves from the flattering and
+almost universal idea that parents are true originators or creators of
+copies of themselves. But the main truth, if not the whole truth, is
+that they are merely the transmitters of types of which they and their
+offspring are alike more or less similarly moulded resultants. A parent
+is a trustee. He transmits, not himself and his own modifications, but
+the stock, the type, the representative elements, of which he is a
+product and a custodian in one. It seems probable that he has no more
+definite or "particulate" influence over the reproductive elements
+within him than a mother over the embryo or a vessel over its cargo.
+Parent and offspring are like successive copies of books printed from
+the same "type." A battered letter in the "type" will display its
+effects in both earlier and later copies alike, but a purely extraneous
+or acquired flaw in the first copy is not necessarily repeated in
+subsequent copies. Unlike printer's type, however, the material source
+of heredity is of a fluctuating nature, consisting of competing elements
+derived from two parents and from innumerable ancestors.
+
+Galton compares parent and child to successive pendants on the same
+chain. Weismann likens them to successive offshoots thrown up by a long
+underground root or sucker. Such comparisons indicate the improbability
+of acquired modifications being transmitted to offspring.
+
+That parts are developed in offspring independently of those parts in
+parents is clear. Mutilated parents transmit parts which they do not
+possess. The offspring of young parents cannot inherit the later stages
+of life from parents who have not passed through them. Cases of remote
+reversion or atavism show that ancestral peculiarities can transmit
+themselves in a latent or undeveloped condition for hundreds or
+thousands of generations. Many obvious facts compelled Darwin to suppose
+that vast numbers of the reproductive gemmules in an individual are not
+thrown off by his own cells, but are the self-multiplying progeny of
+ancestral gemmules. Galton restricts the production of gemmules by the
+personal structure to a few exceptional cases, and would evidently like
+to dispense with pangenesis altogether, if he could only be sure that
+acquired characters are never inherited. Weismann entirely rejects
+pangenesis and the inheritance of acquired characters. This enables him
+to explain heredity by his theory of the "Continuity of the
+Germ-plasm."[67] Parent and offspring are alike successive products or
+offshoots of this persistent germ-substance, which obviously would not
+be correspondingly affected by modifications of parts in parents, and so
+would render the transmission of acquired characters impossible.
+
+
+INVERSE INHERITANCE.
+
+Mr. Galton contends that the reproductive elements become sterile when
+used in forming and maintaining the individual, and that only a small
+proportion of them are so used.[68] He holds that the next generation
+will be formed entirely, or almost entirely, from the residue of
+undeveloped germs, which, not having been employed in the structure and
+work of the individual, have been free to multiply and form the
+reproductive elements whence future individuals are derived. Hence the
+singular inferiority not infrequently displayed by the children of men
+of extraordinary genius, especially where the ancestry has been only of
+a mediocre ability. The valuable germs have been used up in the
+individual, and rendered sterile in the structure of his person. Hence,
+too, the "strong tendency to deterioration in the transmission of every
+exceptionally gifted race." Mr. Galton's hypothesis "explains the fact
+of certain diseases skipping one or more generations," and it "agrees
+singularly well with many classes of fact;" and it is strongly opposed
+to the theory of use-inheritance. The elements which are used die almost
+universally without germ progeny: the germs which are _not_ used are the
+great source of posterity. Hence, when the germs or gemmules which
+achieve development are either better or worse than the residue, the
+qualities transmitted to offspring will be of an inverse character. If
+brain-work attracts, develops _and sterilizes_ the best gemmules, the
+ultimate effect of education on the intellect of posterity may differ
+from its immediate effect.
+
+
+EARLY ORIGIN OF THE OVA.
+
+As the ova are formed at as early a period as the rest of the maternal
+structure, Galton notices that it seems improbable that they would be
+correspondingly affected by subsequent modifications of parental
+structure. Of course it is not certain that this is a valid argument. We
+know that the paternal half of the reproductive elements does not enter
+the ovum till a comparatively late stage in its history, and it is quite
+possible that maternal elements or gemmules may also enter the ovum from
+without. If reproductive elements were confined to one special part or
+organ, we should be unable to explain the reproduction of lost limbs in
+salamanders, and the persistent effect of intercrossing on subsequent
+issue by the same mother, and the propagation of plants from shoots, or
+of the begonia from minute fragments of leaves, or the development of
+small pieces of water-worms into complete animals.
+
+
+MARKED EFFECTS OF USE AND DISUSE ON THE INDIVIDUAL.
+
+These are, to some extent, an argument against the cumulative
+inheritance of such effects. When a nerve atrophies from disuse, or a
+duct shrivels, or bone is absorbed, or a muscle becomes small or flabby,
+it proves, so far, that the average effect of use through enormous ages
+is _not_ transmitted. When the fibula of a dog's leg thickens by 400 per
+cent. to a size "equal to or greater than" that of the removed tibia
+which previously did the work,[69] it shows that in spite of disuse for
+countless generations, the "almost filiform" bone has retained a
+potentiality of development which is fully equal to that possessed by
+the larger one which has been constantly used. When, after being reared
+on the ailanthus, the caterpillars of the _Bombyx hesperus_ die of
+hunger rather than return to their natural food, the inherited effect of
+ancestral habit does not seem to be particularly strong. Neither is
+there any strongly-inherited effect of long-continued ancestral wildness
+in many animals which are easily tamed.
+
+
+WOULD NATURAL SELECTION FAVOUR USE-INHERITANCE?
+
+If use-inheritance is really one of the factors of evolution, it is
+certainly a subordinate one, and an utterly helpless one, whenever it
+comes into conflict with the great ruling principle of Selection. Would
+this dominant cause of evolution have favoured a tendency to
+use-inheritance if such had appeared, or would it have discouraged and
+destroyed it? We have already seen that use-inheritance is unnecessary,
+since natural selection will be far more effective in bringing about
+advantageous modifications; and if it can be shown that use-inheritance
+would often be an evil, it then becomes probable that on the whole
+natural selection would more strongly discourage and eliminate it as a
+hostile factor than it might occasionally favour such a tendency as a
+totally unnecessary aid.
+
+
+USE-INHERITANCE AN EVIL.
+
+Use-inheritance would crudely and indiscriminately proportion parts to
+actual work done--or rather to the varying _nourishment and growth_
+resulting from a multiplicity of causes--and this in its various details
+would often conflict most seriously with the real necessities of the
+case, such as occasional passive strength, or appropriate shape,
+lightness and general adaptation. If its accumulated effects were not
+corrected by natural or sexual selection, horns and antlers would
+disappear in favour of enlarged hoofs. The elephant's tusks would become
+smaller than its teeth. Men would have callosities for sitting on, like
+certain monkeys, and huge corns or hoofs for walking on. Bones would
+often be modified disastrously. Thus the condyle of the human jaw would
+become larger than the body of the jaw, because as the fulcrum of the
+lever it receives more pressure. Some organs (like the heart, which is
+always at work) would become inconveniently or unnecessarily large.
+Other absolutely indispensable organs, which are comparatively passive
+or are very seldom used, would dwindle until their weakness caused the
+ruin of the individual or the extinction of the species. In eliminating
+various evil results of use-inheritance, natural selection would be
+eliminating use-inheritance itself. The displacement of Lamarck's theory
+by Darwin's shows that the effects of use-inheritance often differ from
+those required by natural selection; and it is clear that the latter
+factor must at least have reduced use-inheritance to the very minor
+position of comparative feebleness and harmlessness assigned to it by
+Darwin.
+
+Use-inheritance would be ruinous through causing unequal variation in
+co-operative parts--of which Mr. Spencer may accept his own instances of
+the jaws and teeth, and the cave-crab's lost eyes and persistent
+eye-stalks, as typical examples. That the variation would be unequal
+seems almost self-evident from the varying rapidity and extent of the
+effects of use and disuse on different tissues and on different parts of
+the general structure. The optic nerve may atrophy in a few months from
+disuse consequent on the loss of the eye. Some of the bones of the
+rudimentary hind legs of the whale are still in existence after disuse
+for an enormous period. Evidently use-inheritance could not equally
+modify the turtle and its shell, or the brain and its skull; and in
+minor matters there would be the same incongruity of effect. Thus, if
+the molar teeth lengthened from extra use the incisors could not meet.
+Unequal and indiscriminate variation would throw the machinery of the
+organism out of gear in innumerable ways.
+
+Use-inheritance would perpetuate various evils. We are taught, for
+instance, that it perpetuates short-sight, inferior senses, epilepsy,
+insanity, nervous disorders, and so forth. It would apparently transmit
+the evil effects of over-exertion, disuse, hardship, exposure, disease
+and accident, as well as the defects of age or immaturity.
+
+Would it not be better on the whole if each individual took a fresh
+start as far as possible on the advantageous typical lines laid down by
+natural selection? Through the long stages of evolution from primaeval
+protoplasm upwards, such species as were least affected by
+use-inheritance would be most free to develop necessary but seldom-used
+organs, protective coverings such as shells or skulls, and natural
+weapons, defences, ornaments, special adaptations, and so forth; and
+this would be an advantage--for survival would obviously depend on the
+_importance_ of a structure or faculty in deciding the struggle for
+existence and reproduction, and not on the total amount of its using or
+nourishment. If natural selection had on the whole favoured this
+officious ally and frequent enemy, surely we should find better evidence
+of its existence.
+
+Without laying undue stress upon the evil effects of use-inheritance, a
+careful examination of them in detail may at least serve to
+counter-balance the optimistic _a priori_ arguments for belief in that
+plausible but unproven factor of evolution.
+
+The benefits derivable from use-inheritance are largely illusory. The
+effects of _use_, indeed, are generally beneficial up to a certain
+point; for natural selection has sanctioned or evolved organs which
+possess the property or potentiality of developing to the right extent
+under the stimulus of use or nourishment. But use-_inheritance_ would
+cumulatively alter this individual adaptability, and would tend to fix
+the size of organs by the average amount of ancestral use or disuse
+rather than by the actual requirements of the individual. Of course
+under changed conditions involving increased or lessened use of parts it
+might become advantageous; but even here it may prove a decided
+hindrance to adaptive evolution in some respects as well as an
+unnecessary aid in others. Thus in the case of animals becoming heavier,
+or walking more, it would _lengthen_ the legs although natural selection
+might require them to be shortened. In the Aylesbury duck and the Call
+duck, if use-inheritance has increased the dimensions of the bones and
+tendons of the leg, natural selection has had to counteract this
+increase so far as length is concerned, and to effect 8 per cent. of
+shortening besides. If use-inheritance thickens bones without
+proportionally lengthening them, it would hinder rather than help the
+evolution of such structures as the long light wings of birds, or the
+long legs and neck of the giraffe or crane.
+
+
+VARIED EFFECTS OF USE AND DISUSE.
+
+The changes which we somewhat roughly and empirically group together as
+the effects of "use and disuse" are of widely diverse character. Thus
+bone, as the physiological fact, thickens under _alternations_ of
+pressure (and the consequent increased flow of nourishment), but
+atrophies under a steadily continued pressure; so that if the use of a
+bone involved continuous pressure, the effect of such use would be a
+partial or total absorption of that bone. Darwin shows that bone
+lengthens as well as thickens from carrying a greater weight, while
+tension (as seen in sailors' arms, which are used in pulling) appears to
+have an equally marked effect in shortening bones (_Descent of Man_, p.
+32). Thus different kinds of use may produce opposite results. The
+cumulative inheritance of such effects would often be mischievous. The
+limbs of the sloth and the prehensile tail of the spider monkey would
+continually grow shorter, while the legs of the evolving elephant or
+rhinoceros might lengthen to an undesirable extent. Such cumulative
+tendencies of use-inheritance, if they exist, are obviously well kept
+under by natural selection.
+
+Although the ultimate effect of use is generally growth or enlargement
+through increased flow of blood, the first effect usually is a loss of
+substance, and a consequent diminution of size and strength. When the
+loss exceeds the growth, use will diminish or deteriorate the part used,
+while disuse would enlarge or perfect it. Teeth, claws, nails, skin,
+hair, hoofs, feathers, &c., may thus be worn away faster than they can
+renew themselves. But this wearing away usually stimulates the repairing
+process, and so increases the rate of growth; that is, it will increase
+the size produced, if not the size retained. Which effect of use does
+use-inheritance transmit in such cases--the increased rate of growth, or
+the dilapidation of the worn-out parts? We can hardly suppose that both
+these effects of use will be inherited. Would shaving destroy the beard
+in time or strengthen it? Will the continued shearing of sheep increase
+or lessen the growth of wool? What will be the ultimate effect of
+plucking geese's quills, and of the eider duck's abstraction of the down
+from her breast? If the mutilated parts grow stronger or more
+abundantly, why were the motmot's feathers alleged to be narrowed by the
+inherited effects of ancestral nibbling?
+
+The "use" or "work" or "function" of muscles, nerves, bones, teeth,
+skin, tendon, glands, ducts, eyes, blood corpuscles, cilia, and the
+other constituents of the organism, is as widely different as the
+various parts are from each other, and the effects of their use or
+disuse are equally varied and complicated.
+
+
+USE-INHERITANCE IMPLIES PANGENESIS.
+
+How could the transmission of these varied effects to offspring be
+accounted for? Is it possible to believe, with Mr. Spencer, that the
+effects of use and disuse on the parts of the personal structure are
+simultaneously registered in corresponding impressions on the seminal
+germs? Must we not feel, with Darwin apparently,[70] that the _only_
+intelligible explanation of use-inheritance is the hypothesis of
+Pangenesis, according to which each modified cell, or physiological
+unit, throws off similarly-modified gemmules or parts of itself, which
+ultimately reproduce the change in offspring? If we reject pangenesis,
+it becomes difficult to see how use-inheritance can be possible.
+
+
+PANGENESIS IMPROBABLE.
+
+The more important and best-known phenomena of heredity do not require
+any such hypothesis, and leading facts (such as atavism, transmission of
+lost parts, and the general non-transmission of acquired characters) are
+so adverse to it that Darwin has to concede that many of the
+reproductive gemmules are atavistic, and that by continuous
+self-multiplication they may preserve a practical "continuity of
+germ-substance," as Weismann would term it. The idea that the
+relationship of offspring to parent is one of direct descent is, as
+Galton tells us, "wholly untenable"; and the only reason he admits some
+supplementary traces of pangenesis into his "Theory of Heredity,"[71] is
+that he may thus account for the more or less questionable cases of the
+transmission of acquired characters. But there appears to be no
+necessity even for this concession. We ought therefore to dispense with
+the useless and gratuitous hypothesis that cells multiply by throwing
+off minute self-multiplying gemmules, as well as by the well-known
+method of self-division. If pangenesis occurs, the transmission of
+acquired characters ought to be a prominent fact. The size, strength,
+health and other good or evil qualities of the cells could hardly fail
+to exercise a marked and corresponding effect upon the size and quality
+of the reproductive gemmules thrown off by those cells. The direct
+evidence tends to show that these free gemmules do not exist.
+Transfusion of blood has failed to affect inheritance in the slightest
+degree. Pangenesis, with its attraction of gemmules from all parts of
+the body into the germ-cells, and the free circulation of gemmules in
+the offspring till they hit upon or are attracted by the particular cell
+or cells, with which alone they can readily unite, seems a less feasible
+theory and less in conformity with the whole of the facts than an
+hypothesis of germ-continuity which supposes that the development of the
+germ-plasm and of the successive self-dividing cells of the body
+proceeds from within. Darwin's keen analogy of the fertilization of
+plants by pollen renders development from without conceivable, but as
+there are no insects to convey gemmules to their destination, each kind
+of gemmule would have to be exceedingly numerous and easily attracted
+from amongst an inconceivable number of other gemmules. Arguments
+against pangenesis can also be drawn from the case of neuter insects--a
+fact which seems to have escaped Darwin's notice, although he had seen
+how strongly that case was opposed to the doctrine which is the
+essential basis of the theory of pangenesis.
+
+
+SPENCER'S EXPLANATION OF USE-INHERITANCE.
+
+Mr. Spencer's explanation of the inheritance of the effects of use and
+disuse (p. 36) is that "while generating a modified _consensus_ of
+functions and of structures, the activities are at the same time
+impressing this modified _consensus_ on the sperm-cells and germ-cells
+whence future individuals are to be produced"--a proposition which reads
+more like metaphysics than science. Difficult to understand or believe
+in ordinary instances, such _consensus_-inheritance seems impossible in
+cases like that of the hive-bee. Can we suppose that the _consensus_ of
+the activities of the working bee impresses itself on the sperm-cells
+of the drones and on the germ-cells of the carefully secluded queen?
+Buechner thinks so, for he says: "Although the queens and drones do not
+now work, yet the capacities inherited from earlier times still remain
+to them, especially to the former, and are kept alive and fresh by the
+impressions constantly made upon them during life, and they are thus in
+a position to transmit them to posterity." Surely it is better to
+abandon a cherished theory than to be compelled to defend it by
+explanations which are as inconsistent as they are inadequate. New
+capacities are developed as well as old ones kept fresh. The massacre or
+expulsion of the drones would have to impress itself on the germ-cells
+of an onlooking queen, and the imprisonment of the queen on the
+sperm-cells of the drones--and in such a way, moreover, as to be
+afterwards developed into action in the neuters only. And
+use-inheritance all the while is being thoroughly overpowered by
+impression-inheritance--by the full transmission of that which is merely
+seen in others! If such a law prevails, one may feel cold because an
+ancestor thought of the frosty Caucasus. None of this absurdity would
+arise if it were clearly seen that a parent is only a trustee--that
+transmission and development are perfectly distinct--that parental
+modifications are irrelevant to those transmitted to offspring.
+
+
+FOOTNOTES:
+
+[67] _Essays on Heredity_, p. 104. Weismann's theory is clear, simple
+and convenient, but incomplete; for, unlike Darwin's theory of
+pangenesis, it scarcely attempts any real explanation of the extremely
+complex potentialities possessed by the reproductive elements. Perhaps
+we might retain Darwin's self-multiplying gemmules without supposing
+them to be thrown off by the cells, which will no longer be credited
+with _two_ modes of multiplication. These minute germs or gemmules may
+have been evolved by natural selection playing upon the sample germs
+that achieve development; and they may exist either separately, or
+(preferably but perhaps not invariably) in aggregates to form Weismann's
+germ-plasm.
+
+[68] _Contemporary Review_, Dec., 1875, p. 88.
+
+[69] _Variation of Animals and Plants under Domestication_, ii. 286.
+
+[70] _Variation of Animals and Plants under Domestication_, ii. 388,
+398, 367; _Life and Letters_, iii. 44.
+
+[71] _Contemporary Review_, Dec., 1875, pp. 94, 95.
+
+
+
+
+CONCLUSIONS.
+
+
+USE-INHERITANCE DISCREDITED AS UNNECESSARY, UNPROVEN, AND IMPROBABLE.
+
+General experience teaches that acquired characters are not usually
+inherited; and investigation shows that the apparent exceptions to this
+great rule are probably fallacious. Even the alleged instances of
+use-inheritance culled by such great and judicious selectors as Darwin
+and Spencer break down upon examination; for they can be better
+explained without use-inheritance than with it. On the other hand, the
+adverse facts and considerations are almost strong enough to prove the
+actual non-existence of such a law or tendency. There is no need to
+undertake the apparently impossible task of demonstrating an absolute
+negative. It will be enough to ask that the Lamarckian factor of
+use-inheritance shall be removed from the category of accredited factors
+of evolution to that of unnecessary and improbable hypotheses. The main
+explanation or source of the fallacy may be found in the fact that
+natural selection frequently imitates some of the more obvious effects
+of use and disuse.
+
+
+MODERN RELIANCE ON USE-INHERITANCE MISPLACED.
+
+Modern philanthropy--so far at least as it ever studies ultimate
+results--constantly relies on this ill-founded belief as its
+justification for ignoring the warnings of those who point out the
+ultimately disastrous results of a systematic defiance or reversal of
+the great law of natural selection. This reliance finds strong support
+in Mr. Spencer's latest teachings, for he holds that the inheritance of
+the effects of use and disuse takes place universally, and that it is
+now "the chief factor" in the evolution of civilized man (pp. 35, 74,
+iv)--natural selection being quite inadequate for the work of
+progressive modification. Practically he abandons the hope of evolution
+by natural selection, and substitutes the ideal of a nation being
+"modified _en masse_ by transmission of the effects" of its institutions
+and habits. Use-inheritance will "mould its members far more rapidly and
+comprehensively" than can be effected by the survival of the fittest
+alone.
+
+But could we rely upon the aid of use-inheritance if it really were a
+universal law and not a mere simulation of one? Let us consider some of
+the features of this alleged factor of evolution, seeing that it is
+henceforth to be our principal means of securing the improvement of our
+species and our continued adaptation to the changing conditions of a
+progressive civilization.
+
+It is curiously uncertain and irregular in its action. It diminishes or
+abolishes some structures (such as jaws or eyes) without correspondingly
+diminishing or abolishing other equally disused and closely related
+parts (such as teeth, or eye-stalks). It thickens ducks' leg-bones while
+allowing them to shorten. It shortens the disused wing-bones of ducks
+and the leg-bones of rabbits while allowing them to thicken; and yet in
+other cases it greatly reduces the thickness of bones without shortening
+them. It transmits tameness most powerfully in an animal which usually
+cannot acquire it. It aids in webbing the feet of water-dogs, but fails
+to web the feet of the water-hen or to remove the web in the feet of
+upland geese.[72] It allows the disused fibula to retain a potentiality
+of development fully equal to that possessed by the long-used tibia. It
+lengthens legs because they are used in supporting the body, and
+shortens arms because they are used in pulling. Whether it enlarges
+brain if used in one way and diminishes it if used in another, we cannot
+tell; but it must obviously deaden nervous sensibilities in some cases
+and intensify them in others. It enlarges hands long before they are
+used, and thickens soles long before the time for walking on them. At
+the same time, as if by an oversight, it so delays its transmission of
+the habit of walking on these thickened soles, that the gradual and
+tedious acquisition of the non-transmitted habit costs the infant much
+time and trouble and often some pain and danger. Yet where aided by
+natural selection, as with chickens and foals, it transmits the habit in
+wonderful perfection and at a remarkably early date. It transmits new
+paces in horses in a single generation, but fails to perpetuate the
+songs of birds. It modifies offspring like parents, and yet allows the
+formation of two reproductive types in plants, and of two or more types
+widely different from the parents in some of the higher insects. It is
+said to be indispensable for the co-ordinated development of man and the
+giraffe and the elk, but appears to be unnecessary for the evolution and
+the maintenance of wonderful structures and habits and instincts in a
+thousand species of ants and bees and termites. It is the only possible
+means of complex evolution and adaptation of co-operative parts, and yet
+in Mr. Spencer's most representative case it renders such important
+parts as teeth and jaws unsuited for each other, and is said to ruin the
+teeth by the consequent overcrowding and decay. It survives amidst a
+general "lack of recognised evidence," and only seems to act usefully
+and healthily and regularly in quarters where it can least easily be
+distinguished from other more powerful and demonstrable factors of
+evolution. So little does it care to display its powers where they would
+be easily verifiable as well as useful that practical breeders ignore
+it. So slight is its independent power that it seems to allow natural
+selection or sexual selection or artificial selection to modify
+organisms in sheer defiance of its utmost opposition, just as readily as
+they modify organisms in other directions with its utmost help. If it
+partially perpetuates and extends the pecked-out indentations in the
+motmot's tail feathers, it on the other hand fails to transmit the
+slightest trace of mutilation in an almost infinite number of ordinary
+cases, and even where the mutilation is repeated for a hundred
+generations; and it apparently repairs rather than transmits the
+ordinary and oft-repeated losses caused by plucking hair, down and
+feathers, and the wear and tear of claws, teeth, hoofs and skin.
+
+It is often mischievous as well as anomalous in its action. Under
+civilization with its division of labour, the various functions of mind
+and body are very unequally exercised. There is overwork or misuse of
+one part and disuse and neglect of others, leading to the partial
+breakdown or degeneration of various organs and to general deterioration
+of health through disturbed balance of the constitution. The brain, or
+rather particular parts of it, are often over-stimulated, while the body
+is neglected. In many ways education and civilization foster nervousness
+and weakness, and undermine the rude natural health and spirits of the
+human animal. Alcohol, tobacco, tea, coffee, extra brain work, late
+hours, dissipation, overwork, indoor life, division of labour,
+preservation of the weak, and many other causes, all help to injure the
+modern constitution; so that the prospect of cumulative intensification
+of these evils by the additional influence of use-inheritance is not an
+encouraging one. It is true that modern progress and prosperity are
+improving the people in various respects by their direct action; but if
+use-inheritance has any share in effecting this improvement it must also
+transmit increased wants and more luxurious habits, together with such
+evils as have already been referred to. As depicted by its defenders,
+use-inheritance transmits evils far more powerfully and promptly than
+benefits. It transmits insanity and shattered nerves rather than the
+healthy brain which preceded the breakdown. It perpetuates, and
+cumulatively intensifies, a deterioration in the senses of civilized
+men, but it fails to perpetuate the rank vigour of various plants when
+too well nourished, or the flourishing condition of various animals when
+too fat or when tamed. It already transmits the short-sight caused by so
+modern an art as watchmaking, but so fails to transmit the
+long-practised art of seeing (as it does of walking and talking) that
+vision is worse than useless to a man until he gradually acquires the
+necessary but non-transmitted associations of sensation and idea by his
+own experience. In a well-known case, a blind man on gaining his sight
+by an operation said that "all objects seemed to touch his eyes, as what
+he felt did his skin"--so little had the universal experience of
+countless ages impressed itself on his faculties. Under normal healthy
+conditions use-inheritance is so slow in its action that "several
+generations" must elapse before it produces any appreciable effect, and
+then that effect is only precisely what selection might be expected to
+bring about without its aid. Strong for evil and slow for good, it can
+convey epilepsy promptly in guinea pigs, but transmits the acquirements
+of genius so poorly that our best student of the heredity of genius has
+to account for the frequent and remarkable deterioration of the
+offspring by a theory which is strongly hostile to use-inheritance. It
+would tend to make organisms unworkable by the excessive differences in
+its rate and manner of action on co-operative parts, and by adapting
+these parts to the total amount of nourishment received rather than to
+occasional necessity or actual usefulness. It would tend to stereotype
+habits and convert reason into instinct.
+
+How then can we rely upon use-inheritance for the improvement of the
+race? Even if it is not a sheer delusion, it may be more detrimental as
+a positive evil than it is advantageous as an unnecessary benefit; and
+as a normal modifying agent it is miserably weak and untrustworthy in
+comparison with the powerful selective influences by which nature and
+society continually and inevitably affect the species for good or for
+evil. The effects of use and disuse--rightly directed by education in
+its widest sense--must of course be called in to secure the highly
+essential but nevertheless _superficial, limited, and partly deceptive_
+improvement of individuals and of social manners and methods; but as
+this artificial development of already existing potentialities does not
+directly or readily tend to become congenital, it is evident that some
+considerable amount of natural or artificial selection of the more
+favourably varying individuals will still be the only means of securing
+the race against the constant tendency to degeneration which would
+ultimately swallow up all the advantages of civilization. The selective
+influences by which our present high level has been reached and
+maintained may well be modified, but they must not be abandoned or
+reversed in the rash expectation that State education, or State feeding
+of children, or State housing of the poor, or any amount of State
+socialism or public or private philanthropy, will prove permanently
+satisfactory substitutes. If ruinous deterioration and other more
+immediate evils, are to be avoided, the race must still be to the swift
+and the battle to the strong. The healthy Individualism so earnestly
+championed by Mr. Spencer must be allowed free play. Open competition,
+as Darwin teaches, with its survival and multiplication of the fittest,
+must be allowed to decide the battle of life independently of a foolish
+benevolence that prefers the elaborate cultivation and multiplication of
+weeds to the growth of corn and roses. We are trustees for the countless
+generations of the future. If we are wise we shall trust to the great
+ruling truths that we assuredly know, rather than to the seductive
+claims of an alleged factor of evolution for which no satisfactory
+evidence can be produced.
+
+
+THE END.
+
+RICHARD CLAY AND SONS, LIMITED, LONDON AND BUNGAY.
+
+
+FOOTNOTES:
+
+[72] Professor Romanes had casts made of the feet of upland geese, and
+could not detect any diminution as compared with the web of other geese
+in relation to the toes.
+
+
+
+
+NATURE SERIES.
+
+
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